BJD
British Journal of Dermatology
E P I DE M I O L O G Y A N D HE A L T H S E R V IC E S RE SE AR CH
Use of health care services by patients with psoriasis: a population-based study L.-T. Kao,1,2 K.-H. Wang,3 H.-C. Lin,2,4 H.-C. Li,4 S. Yang5 and S.-D. Chung2,6,7 1
Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan Sleep Research Center, 3Department of Dermatology and 4School of Health Care Administration, Taipei Medical University Hospital, Taipei, Taiwan 5 Irvine School of Medicine, University of California, Irvine, CA, U.S.A. 6 Division of Urology, Department of Surgery, Far Eastern Memorial Hospital, No.21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City 220, Taiwan 7 School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan 2
Summary Correspondence Shiu-Dong Chung. E-mail: [email protected]
Accepted for publication 24 September 2014
Funding sources None.
Conflicts of interest None declared. H.-C.L. and S.-D.C. contributed equally to this study. DOI 10.1111/bjd.13442
Background Although psoriasis is seldom life threatening, very few studies have compared differences in health care service use between patients with and without psoriasis. Objectives To investigate differences in health care service use between patients with and without psoriasis. Methods Patient details and data on their use of health services were retrieved from the Taiwan Longitudinal Health Insurance Database 2000. We included 3649 patients with psoriasis and 3649 without it. Each patient was followed for a 1-year period to estimate their utilization of health care resources. Student t-tests were used to compare differences in health care services use between patients with and without psoriasis. Results For dermatology services, patients with psoriasis had significantly more outpatient visits (35 vs. 09), and higher outpatient and total costs (US$14800 vs. US $1220 and US$58160 vs. US$34720, respectively) than those without psoriasis. For nondermatology services, patients with psoriasis had more outpatient visits (213 vs. 176), and higher outpatient and total costs (US$90460 vs. US$66350 and US$133550 vs. US$99830, respectively) than those without psoriasis. For overall health care service use, patients with psoriasis had significantly more outpatient visits (248 vs. 185; P < 001) and greater total costs (US$191710 vs. US $134560; P < 001) than those without psoriasis. This indicates that the total cost was about 14-fold greater for patients with psoriasis than those without it. Conclusions Patients with psoriasis used health care services significantly more often than those without psoriasis.
What’s already known about this topic?
• •
Although there are reports in the literature on the economic burden of psoriasis, few studies have compared differences in health care services use between patients with psoriasis and those without it. Only one study has previously reported that patients with psoriasis incur greater health care costs than a general group of patients.
What does this study add?
• • 1346
With regard to both dermatology and nondermatology services, patients with psoriasis had significantly more outpatient visits, and greater outpatient and total costs than those without it. The total cost for all health services was about 14-fold greater for patients with psoriasis than those without it.
British Journal of Dermatology (2015) 172, pp1346–1352
© 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1347
Psoriasis is the most prevalent autoimmune disorder worldwide.1 Various studies have reported that psoriasis affects > 2% of adults in the U.S.A.2,3 Moreover, the prevalence of psoriasis has been reported to range from 06% to 65% in different European regions.2 Although psoriasis is seldom life threatening, some studies have demonstrated that psoriasis incurs tremendous financial burden on individuals and healthcare systems.4–6 Therefore, estimating the potential economic burden on patients with psoriasis and their utilization of medical services has become an urgent issue. Previous studies have attempted to investigate the economic burden of psoriasis.7–16 For example, a large study from the U.S.A. reported that patients with psoriasis incurred significantly greater total annual health care costs (US$5529 vs. US $3509), medical costs and drug costs than the general population.8 In Germany, one multicentre study found that the total annual direct cost for patients with plaque-type psoriasis was €5397.11 Retrospective research in Switzerland investigated moderate-to-severe psoriasis, and found that patients had fourfold higher costs than those with mild psoriasis.9 Furthermore, an Italian study reported that the direct cost of psoriasis was €5690 per patient per year.10 However, although many studies have explored the costs associated with psoriasis, few have compared differences in the utilization of health care services between patients with psoriasis and those without it. Additionally, all such studies have been conducted in Western countries, and studies of health care service utilization attributable to patients with psoriasis in Asian countries are lacking. The main purpose of this population-based study was to investigate differences in health care service utilization in Taiwan between patients with psoriasis and those without it. We also compared differences in the utilization of dermatology and nondermatology services between these patients. We expected to be able to evaluate the financial burdens for patients with psoriasis, and provide some advice for health policy decision makers.
Patients and methods Database Sampled patients and data on their use of health services were retrieved from the Longitudinal Health Insurance Database (LHID) 2000. The LHID2000 includes longitudinal data on medical claims for 1 million enrollees since the beginning of the Taiwan National Health Insurance (NHI) programme in 1995. These enrollees were randomly selected from all enrollees listed in the 2000 Registry of Beneficiaries (n = 2372 million) under the NHI programme. To date, many studies using data from the NHI programme have been published in international peer-reviewed journals.17 This study was exempt from full review by the institutional review board of Taipei Medical University because the LHID2000 consists of deidentified secondary data released to the public for research purposes. © 2014 British Association of Dermatologists
Study sample This cross-sectional study included a study group and a comparison group. For the study group, we first identified 4417 patients who had received a diagnosis of psoriasis [International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 696] in ambulatory care visits (including outpatient departments of hospitals and clinics) between 1 January and 31 December 2010. We defined the date of their first visit for treatment of psoriasis during 2010 as the index date. In order to ensure equal follow-up periods (1 year) for all selected patients, we further excluded those who died during 2011 (n = 100). In order to limit the study sample to the adult population, we also excluded those aged < 18 years (n = 668). Ultimately, 3649 patients with psoriasis were included in the study group. Likewise, we retrieved comparison patients from the Registry of Beneficiaries of the LHID2000. We first identified all those who had ambulatory care visits (including hospital and clinic outpatient departments) between 1 January and 31 December 2010. We then excluded those who had a history of psoriasis since the implementation of the NHI programme. We further selected 3649 comparison patients (one comparison patient per patient with psoriasis) from the remaining enrollees. Comparison patients were matched with patients with psoriasis by sex, age and the month of index date by the SAS PROC SURVEYSELECT program (SAS Institute Inc., Cary, NC, U.S.A.). For comparison patients, we assigned the date of their first use of medical services in 2010 as the index date. For the study group, the month of index date was the month when study patients received their first treatment for psoriasis. For the comparison group the month of index date was the month in 2010 in which comparison subjects first made use of a medical service. Ultimately, this study included 7298 patients (3649 with psoriasis and 3649 without). Of the 3649 patients with psoriasis, 178 (49%) were classified as having psoriatic arthritis based on ICD-9-CM (code 6961). In addition, we further categorized the patients with psoriasis into two groups: (i) those with moderate-to-severe psoriasis who had received any systemic medications or phototherapy (n = 510; 140%); and (ii) those with mild psoriasis who had not received any systemic medications or phototherapy (n = 3139; 860%). Variables of interest To estimate their use of health care resources, each patient was individually followed for a 1-year period starting from their index date. Health care resource use variables were number of outpatient visits and inpatient days, and mean costs of out- and inpatient treatments. We further divided health care resource use into dermatology and nondermatology services. Statistical analysis SAS for Windows version 8.2 (SAS Institute Inc.) was used for the statistical analyses. We calculated the mean and SD of all British Journal of Dermatology (2015) 172, pp1346–1352
1348 Health care services use by patients with psoriasis, L.-T. Kao et al.
variables of health care resource use. We used v2 tests to compare differences in patients’ monthly income, geographical location (northern, central, eastern and southern Taiwan) and urbanization level (five levels: 1 = most urbanized, 5 = least urbanized) between patients and controls. The northern, southern and central areas of Taiwan are more populated and industrial than the eastern area.18 Furthermore, we used Student t-tests to explore differences in variables of health care resource use between patients with psoriasis and those without. Differences were considered significant for two-sided Pvalues of ≤ 005. This study complied with Strengthening the Reporting of Observational Studies in Epidemiology guidelines.19
Results The mean age of the 7298-person study sample was 452 178 years. After matching for sex and age, there were no statistically significant differences between patients with psoriasis and those without with regard to level of urbanization (P = 050), monthly income (P = 048) and geographical region (P = 075) (Table 1). Table 1 Demographic characteristics of patients with psoriasis and comparison patients
Variable
Patients with psoriasis (n = 3649)
Sex Male 2066 Female 1583 Age (years) 18–24 455 25–34 807 35–44 618 45–54 677 55–64 525 65–74 284 75–84 226 > 85 57 Level of urbanizationa 1 1095 2 967 3 579 4 454 5 554 Monthly income (US$) 1–530 1398 530–830 1162 ≥ 830 1089 Geographical regionb Northern 1767 Central 814 Southern 973 Eastern 95
(566) (434)
Comparison patients (n = 3649) 2066 (566) 1583 (434)
P-value > 100
(125) (221) (169) (186) (144) (78) (62) (16)
455 807 618 677 525 284 226 57
(125) (221) (169) (186) (144) (78) (62) (16)
> 100
(300) (265) (159) (124) (152)
1115 957 597 476 504
(306) (262) (164) (130) (138)
050
(383) (318) (298)
1348 (369) 1193 (327) 1108 (304)
048
(484) (223) (267) (26)
1798 809 959 83
075
(493) (222) (263) (23)
Values given as n (%). a1 = most urbanized, 5 = least urbanized. b In Tawian.
British Journal of Dermatology (2015) 172, pp1346–1352
Table 2 shows the use of health care resources in the 1year period following the index date for patients with psoriasis and those without. With regard to dermatology services, patients with psoriasis had significantly more outpatient visits (35 vs. 09; P < 001) and significantly higher outpatient costs (US$14800 vs. US$1220; P < 001) than comparison patients. This suggests that outpatient costs were about 121-fold greater for patients with psoriasis than for comparison patients. Furthermore, we found that total costs were greater for patients with psoriasis than for comparison patients (US$58160 vs. US$34720; P < 001). However, there was no significant difference in inpatient days or inpatient costs between patients with psoriasis and those without. With regard to nondermatology services, internal medicine, family medicine and Chinese medicine were the major outpatient services used by patients with or without psoriasis. Table 2 Use and costs of health care services within 1 year by patients with psoriasis and comparison patients
Variable
Patients with psoriasis (n = 3649)
Dermatology services Outpatient 35 visits (n) Outpatient 1480 costs (US$) Inpatient 19 days (n) Inpatient 4336 costs (US$) Total costs 5816 (US$) Nondermatology services Outpatient 213 visits (n) Outpatient 9046 costs (US$) Inpatient 18 days (n) Inpatient 4309 costs (US$) Total costs 13355 (US$) All health services Outpatient 248 visits (n) Outpatient 10526 costs (US$) Inpatient 37 days (n) Inpatient 8645 costs (US$) Total costs 19171 (US$)
Comparison patients (n = 3649)
P-value
09 27
< 001
6389
122 442
< 001
100
16 113
029
26621
3350 21435
008
27396
3472 21449 < 001
59
202 29699
176 177
< 001
6635 18041 < 001 16 113
035
26605
3349 21434
009
43423
9983 30616 < 001
99
217 30450 199 53222
185 182
< 001
6757 18068 < 001 32 226
032
6699 42869
009
65979 13456 49698 < 001
Values are given as mean SD.
© 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1349
Additionally, internal medicine, surgery, and obstetrics and gynaecology were commonly used inpatient services (data not shown). Table 2 shows that patients with psoriasis had significantly more outpatient visits (213 vs. 176; P < 001) and significantly higher outpatient costs (US$90460 vs. US $66350; P < 001) than comparison patients. Patients with psoriasis also incurred significantly higher total costs compared with comparison patients (US$13355 vs. US$9983; P < 001). However, the number of inpatient days (18 vs. 16) and inpatient costs of patients with psoriasis (US$43090 vs. US$33490) were not significantly higher than those of the comparison patients. With regard to overall health care service utilization, patients with psoriasis had significantly more outpatient visits (248 vs. 185; P < 001), and significantly higher outpatient (US$105260 vs. US$67570; P < 001) and total costs (US $191710 vs. US$134560; P < 001) than comparison patients. This indicates that total costs were about 14-fold greater for patients with psoriasis than comparison patients. The number of inpatient days (37 vs. 32) and inpatient costs of patients with psoriasis (US$86450 vs. US$66990) were not significantly higher than those of comparison patients. Table 3 shows the differences in health care service utilization between patients with other types of psoriasis and patients with psoriatic arthritis. With regard to the utilization of dermatology services, the number of outpatient visits, outpatient costs, number of inpatient days, inpatient costs and total costs were not significantly different between patients with psoriatic arthritis and patients with other types of psoriasis. With regard to the utilization of nondermatology services, patients with psoriatic arthritis had significantly more outpatient visits (261 vs. 211; P < 001), outpatient costs (US $182280 vs. US$85910; P < 001) and total costs (US $256420 vs. US$127470; P < 001) than patients with other types of psoriasis. However, the number of inpatient days (20 vs. 18) and inpatient costs (US$74140 vs. US$41560) were not significantly different from those of patients with other types of psoriasis. Furthermore, with regard to utilization of all health services, patients with psoriatic arthritis had significantly more outpatient visits (291 vs. 246; P < 001), and higher outpatient (US$205490 vs. US$100300; P < 001) and total costs (US$354670 vs. US$183650) compared with patients with other types of psoriasis. Table 4 shows the differences in the use of health care services between patients with moderate-to-severe psoriasis and those with mild psoriasis. With regard to the use of dermatology services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (71 vs. 29; P < 001), higher outpatient costs (US$58830 vs. US$7650; P < 001), more inpatient days (29 vs. 17; P = 002) and higher total costs (US$114440 vs. US$49020; P < 001) than patients with mild psoriasis. Similarly, with regard to nondermatology services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (254 vs. 206; P < 001), higher outpatient costs (US$139540 vs. US$82480; P < 001), more inpatient days (28 vs. 17; P = 003) and higher total © 2014 British Association of Dermatologists
Table 3 Use and costs of health care services within 1 year by patients with psoriatic arthritis and patients with psoriasis Patients with psoriatic arthritis (n = 172)
Variable
Dermatology services Outpatient 30 visits (n) Outpatient 2321 costs (US$) Inpatient 22 days (n) Inpatient 7505 costs (US$) Total costs 9825 (US$) Nondermatology services Outpatient 261 visits (n) Outpatient 18228 costs (US$) Inpatient 20 days (n) Inpatient 7414 costs (US$) Total costs 25642 (US$) All health services Outpatient 291 visits (n) Outpatient 20549 costs (US$) Inpatient 43 days (n) Inpatient 14918 costs (US$) Total 35467 costs (US$)
Patients with psoriasis (n = 3477)
P-value
35 59
022
1439 6200
023
18 101
062
41068
4179 25696
029
42564
5618 26415
020
57 9415 94
201 32694 92 41073
211 201
< 001
8591 29474 < 001 18 99
077
4156 25678
030
53749 12747 42765 < 001
210
246 217
001
33424 10030 30215 < 001 36 200
069
8335 51370
030
90534 18365 64433
002
185 82136
Values are given as mean SD.
costs (US$194260 vs. US$123690; P < 001) than patients with mild psoriasis. Additionally, with regard to the use of all health services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (325 vs. 236; P < 001), higher outpatient costs (US$198370 vs. US$90130, P < 001), more inpatient days (57 vs. 34, P = 002) and higher total costs (US$30870 vs. US$17271; P < 001) than patients with mild psoriasis. Only inpatient costs for dermatology services, nondermatology services and all health services were not significantly different between patients with moderate-to-severe psoriasis and those with mild psoriasis.
Discussion This population-based study compared the use of medical services between patients with psoriasis and those without. We found that for dermatology services, patients with psoriasis British Journal of Dermatology (2015) 172, pp1346–1352
1350 Health care services use by patients with psoriasis, L.-T. Kao et al. Table 4 Use and costs of health care services within 1 year by patients with moderate-to-severe psoriasis and patients with mild psoriasis
Variable
Patients with moderate-to-severe Patients with mild psoriasis (n = 510) psoriasis (n = 3139) P-value
Dermatology services Outpatient 71 visits (n) Outpatient 5883 costs (US$) Inpatient 29 days (n) Inpatient 5561 costs (US$) Total costs 11444 (US$) Nondermatology services Outpatient 254 visits (n) Outpatient 13954 costs (US$) Inpatient 28 days (n) Inpatient 5472 costs (US$) Total costs 19426 (US$) All health services Outpatient 325 visits (n) Outpatient 19837 costs (US$) Inpatient 57 days (n) Inpatient 11033 costs (US$) Total costs 30870 (US$)
87 14612
29 50
< 001
765 3027
< 001
17 99
002
21986
4137 27298
019
26290
4902 27467
< 001
206 198
< 001
8248 29788
< 001
110
218 28685
17 97
003
21938
4121 27286
021
39076
12369 44015
< 001
236 210
< 001
9013 29995
< 001
108
241 31584
34 196
002
43910
8257 54582
020
57951
17271 67008
< 001
218
Values are given as mean SD.
had fourfold more outpatient visits (35 vs. 09) and 12-fold higher outpatient costs (US$14800 vs. US$1220) compared with patients without psoriasis. Moreover, for nondermatology services, patients with psoriasis had more outpatient visits and higher annual total costs than those without (213 vs. 176 and US$90460 vs. US$66350, respectively). The study demonstrated that patients in Taiwan with psoriasis utilized medical services more than those without. The majority of previous studies concentrated on the direct or indirect costs of psoriasis-associated treatments.8,10,11,14 Nevertheless, very few studies compared the use of health care services between patients with psoriasis and those without. In this study, we found that patients with psoriasis had more outpatient visits, and higher outpatient and total costs for both dermatology and nondermatology services than patients without psoriasis. This might be owing to the occurrence of comorbidities in patients with psoriasis, as the chronic British Journal of Dermatology (2015) 172, pp1346–1352
inflammatory feature of psoriasis has been suggested to be one of the potential risk factors for the progression of comorbidities.20 Several studies have reported that, compared with the general population, patients with psoriasis show a significantly increasing incidence of comorbidities such as arthritis, cardiovascular disease, metabolic syndrome, depressive disorder and so on.20–25 Furthermore, one U.S. study by Crown et al.26 showed that patients with psoriasis who had significantly more comorbidities incurred higher total annual health care costs than those without psoriasis. Therefore, the high incidence of comorbidities associated with psoriasis might explain the increased use of health care services among patients with psoriasis. Patients with psoriatic arthritis had significantly more outpatient visits (261 vs. 211), and higher outpatient and total costs (US$182280 vs. US$85910 and US$256420 vs. US $127470, respectively) for nondermatology services compared with patients with other types of psoriasis. This finding is consistent with a report by Kimball et al.,27 who concluded that patients with comorbidities such as cardiovascular disease, psoriatic arthritis, depression and so on needed to use health care services more often than patients without comorbidities. They also reported that patients with psoriasis who had any comorbidities used more health care resources (e.g. had higher hospitalization rates, more outpatient visits and higher 6-month mean costs of health care) than those with no comorbidities. However, our study showed that patients with psoriatic arthritis did not have significantly more outpatient visits or higher costs for dermatology services than those with other types of psoriasis. It may be that patients with psoriatic arthritis might visit rheumatology rather than dermatology. Moreover, our study found that the patients with moderateto-severe psoriasis had significantly more outpatient visits, higher outpatient costs, more inpatient days and higher total costs for dermatology services, nondermatology services and all health services compared with patients with mild psoriasis. These outcomes are consistent with previous studies that estimated economic burdens for patients with psoriasis.10,14 These studies found that expenses incurred for psoriasis were related to disease severity. The increasing use of dermatology services could be explained by the high costs and lengthy psoriasis treatment. In addition, the high use of nondermatology services might be owing to the likelihood of comorbidities. One study has reported that the burdens of comorbidities increase with rising disease severity among patients with psoriasis.28 Nevertheless, for both dermatology and nondermatology services, our study showed that there were no statistically significant differences in inpatient days and costs between patients with and without psoriasis and between patients with psoriatic arthritis and other types of psoriasis. This might suggest that the comorbidities of patients with psoriasis may not be severe enough to warrant hospitalization. The particular strength of this study is the use of a population-based dataset with a single-payer system and wide health benefit coverage in Taiwan. These characteristics could decrease the effect of a selection bias, provide an adequate © 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1351
sample size and increase the statistical power in identifying different health care service use rates between patients with psoriasis and those without. Moreover, this dataset recorded the total medical costs and utilization information for all study patients since they entered the healthcare system in Taiwan. These features of the dataset reduced the potential for recall bias in the study. Furthermore, most of the included patients in the study are Taiwanese. Prior studies that discuss health care service utilization in patients with psoriasis in Asian countries were lacking. Because psoriasis has a strong genetic component, our outcomes could be generalized to the Asian ethnic group worldwide.29 In addition, our study might be generalized to some countries, such as Canada, Germany, France, South Korea, Japan, the U.K., Sweden and so on as the healthcare systems in these countries have national/public health insurance, similar to the Taiwanese system.30–32 However, because the sources of health care finance, health care providers and insurance coverage rates are dissimilar in different healthcare systems, our study can be generalized cautiously to the countries that are involved in national health services or private insurance systems (e.g. the U.S.A.).31,32 Nevertheless, there are several limitations to our study. Firstly, the cost and utilization analyses in our study were based on records released by the NHI administration. Therefore, we could not evaluate costs if patients with psoriasis did not seek medical care. Additionally, we could not assess costs of over-the-counter drugs as they are not covered by the NHI programme. Secondly, we did not estimate indirect psoriasisassociated costs, such as the loss of productivity caused by absence from work, unemployment and occupational retraining. To our knowledge, there are no accessible records of indirect costs in Taiwan. Thirdly, the algorithm to identify the sensitivity and specificity of the selection of patients with psoriasis has not been previously validated in LHID. However, many previous studies have used this database to identify patients with psoriasis.33–35 Therefore, this method is well recognized in this field of research in Taiwan. We found that patients with psoriasis used health care services significantly more often than the comparison group. Moreover, this outcome was observed for both dermatology and nondermatology services. Patients with moderate-to-severe psoriasis also used health care services more often than patients with mild psoriasis. Our study objectively evaluated the economic burdens of patients with psoriasis. The results of this study may have some important policy implications for medical professionals and policy makers in terms of providing appropriate approaches that could eventually prove to be of significant benefit to the management of this chronic disease. Nevertheless, further studies are warranted to explore the factors contributing to the increased health care use by patients with psoriasis.
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British Journal of Dermatology
E P I DE M I O L O G Y A N D HE A L T H S E R V IC E S RE SE AR CH
Use of health care services by patients with psoriasis: a population-based study L.-T. Kao,1,2 K.-H. Wang,3 H.-C. Lin,2,4 H.-C. Li,4 S. Yang5 and S.-D. Chung2,6,7 1
Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan Sleep Research Center, 3Department of Dermatology and 4School of Health Care Administration, Taipei Medical University Hospital, Taipei, Taiwan 5 Irvine School of Medicine, University of California, Irvine, CA, U.S.A. 6 Division of Urology, Department of Surgery, Far Eastern Memorial Hospital, No.21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City 220, Taiwan 7 School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan 2
Summary Correspondence Shiu-Dong Chung. E-mail: [email protected]
Accepted for publication 24 September 2014
Funding sources None.
Conflicts of interest None declared. H.-C.L. and S.-D.C. contributed equally to this study. DOI 10.1111/bjd.13442
Background Although psoriasis is seldom life threatening, very few studies have compared differences in health care service use between patients with and without psoriasis. Objectives To investigate differences in health care service use between patients with and without psoriasis. Methods Patient details and data on their use of health services were retrieved from the Taiwan Longitudinal Health Insurance Database 2000. We included 3649 patients with psoriasis and 3649 without it. Each patient was followed for a 1-year period to estimate their utilization of health care resources. Student t-tests were used to compare differences in health care services use between patients with and without psoriasis. Results For dermatology services, patients with psoriasis had significantly more outpatient visits (35 vs. 09), and higher outpatient and total costs (US$14800 vs. US $1220 and US$58160 vs. US$34720, respectively) than those without psoriasis. For nondermatology services, patients with psoriasis had more outpatient visits (213 vs. 176), and higher outpatient and total costs (US$90460 vs. US$66350 and US$133550 vs. US$99830, respectively) than those without psoriasis. For overall health care service use, patients with psoriasis had significantly more outpatient visits (248 vs. 185; P < 001) and greater total costs (US$191710 vs. US $134560; P < 001) than those without psoriasis. This indicates that the total cost was about 14-fold greater for patients with psoriasis than those without it. Conclusions Patients with psoriasis used health care services significantly more often than those without psoriasis.
What’s already known about this topic?
• •
Although there are reports in the literature on the economic burden of psoriasis, few studies have compared differences in health care services use between patients with psoriasis and those without it. Only one study has previously reported that patients with psoriasis incur greater health care costs than a general group of patients.
What does this study add?
• • 1346
With regard to both dermatology and nondermatology services, patients with psoriasis had significantly more outpatient visits, and greater outpatient and total costs than those without it. The total cost for all health services was about 14-fold greater for patients with psoriasis than those without it.
British Journal of Dermatology (2015) 172, pp1346–1352
© 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1347
Psoriasis is the most prevalent autoimmune disorder worldwide.1 Various studies have reported that psoriasis affects > 2% of adults in the U.S.A.2,3 Moreover, the prevalence of psoriasis has been reported to range from 06% to 65% in different European regions.2 Although psoriasis is seldom life threatening, some studies have demonstrated that psoriasis incurs tremendous financial burden on individuals and healthcare systems.4–6 Therefore, estimating the potential economic burden on patients with psoriasis and their utilization of medical services has become an urgent issue. Previous studies have attempted to investigate the economic burden of psoriasis.7–16 For example, a large study from the U.S.A. reported that patients with psoriasis incurred significantly greater total annual health care costs (US$5529 vs. US $3509), medical costs and drug costs than the general population.8 In Germany, one multicentre study found that the total annual direct cost for patients with plaque-type psoriasis was €5397.11 Retrospective research in Switzerland investigated moderate-to-severe psoriasis, and found that patients had fourfold higher costs than those with mild psoriasis.9 Furthermore, an Italian study reported that the direct cost of psoriasis was €5690 per patient per year.10 However, although many studies have explored the costs associated with psoriasis, few have compared differences in the utilization of health care services between patients with psoriasis and those without it. Additionally, all such studies have been conducted in Western countries, and studies of health care service utilization attributable to patients with psoriasis in Asian countries are lacking. The main purpose of this population-based study was to investigate differences in health care service utilization in Taiwan between patients with psoriasis and those without it. We also compared differences in the utilization of dermatology and nondermatology services between these patients. We expected to be able to evaluate the financial burdens for patients with psoriasis, and provide some advice for health policy decision makers.
Patients and methods Database Sampled patients and data on their use of health services were retrieved from the Longitudinal Health Insurance Database (LHID) 2000. The LHID2000 includes longitudinal data on medical claims for 1 million enrollees since the beginning of the Taiwan National Health Insurance (NHI) programme in 1995. These enrollees were randomly selected from all enrollees listed in the 2000 Registry of Beneficiaries (n = 2372 million) under the NHI programme. To date, many studies using data from the NHI programme have been published in international peer-reviewed journals.17 This study was exempt from full review by the institutional review board of Taipei Medical University because the LHID2000 consists of deidentified secondary data released to the public for research purposes. © 2014 British Association of Dermatologists
Study sample This cross-sectional study included a study group and a comparison group. For the study group, we first identified 4417 patients who had received a diagnosis of psoriasis [International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 696] in ambulatory care visits (including outpatient departments of hospitals and clinics) between 1 January and 31 December 2010. We defined the date of their first visit for treatment of psoriasis during 2010 as the index date. In order to ensure equal follow-up periods (1 year) for all selected patients, we further excluded those who died during 2011 (n = 100). In order to limit the study sample to the adult population, we also excluded those aged < 18 years (n = 668). Ultimately, 3649 patients with psoriasis were included in the study group. Likewise, we retrieved comparison patients from the Registry of Beneficiaries of the LHID2000. We first identified all those who had ambulatory care visits (including hospital and clinic outpatient departments) between 1 January and 31 December 2010. We then excluded those who had a history of psoriasis since the implementation of the NHI programme. We further selected 3649 comparison patients (one comparison patient per patient with psoriasis) from the remaining enrollees. Comparison patients were matched with patients with psoriasis by sex, age and the month of index date by the SAS PROC SURVEYSELECT program (SAS Institute Inc., Cary, NC, U.S.A.). For comparison patients, we assigned the date of their first use of medical services in 2010 as the index date. For the study group, the month of index date was the month when study patients received their first treatment for psoriasis. For the comparison group the month of index date was the month in 2010 in which comparison subjects first made use of a medical service. Ultimately, this study included 7298 patients (3649 with psoriasis and 3649 without). Of the 3649 patients with psoriasis, 178 (49%) were classified as having psoriatic arthritis based on ICD-9-CM (code 6961). In addition, we further categorized the patients with psoriasis into two groups: (i) those with moderate-to-severe psoriasis who had received any systemic medications or phototherapy (n = 510; 140%); and (ii) those with mild psoriasis who had not received any systemic medications or phototherapy (n = 3139; 860%). Variables of interest To estimate their use of health care resources, each patient was individually followed for a 1-year period starting from their index date. Health care resource use variables were number of outpatient visits and inpatient days, and mean costs of out- and inpatient treatments. We further divided health care resource use into dermatology and nondermatology services. Statistical analysis SAS for Windows version 8.2 (SAS Institute Inc.) was used for the statistical analyses. We calculated the mean and SD of all British Journal of Dermatology (2015) 172, pp1346–1352
1348 Health care services use by patients with psoriasis, L.-T. Kao et al.
variables of health care resource use. We used v2 tests to compare differences in patients’ monthly income, geographical location (northern, central, eastern and southern Taiwan) and urbanization level (five levels: 1 = most urbanized, 5 = least urbanized) between patients and controls. The northern, southern and central areas of Taiwan are more populated and industrial than the eastern area.18 Furthermore, we used Student t-tests to explore differences in variables of health care resource use between patients with psoriasis and those without. Differences were considered significant for two-sided Pvalues of ≤ 005. This study complied with Strengthening the Reporting of Observational Studies in Epidemiology guidelines.19
Results The mean age of the 7298-person study sample was 452 178 years. After matching for sex and age, there were no statistically significant differences between patients with psoriasis and those without with regard to level of urbanization (P = 050), monthly income (P = 048) and geographical region (P = 075) (Table 1). Table 1 Demographic characteristics of patients with psoriasis and comparison patients
Variable
Patients with psoriasis (n = 3649)
Sex Male 2066 Female 1583 Age (years) 18–24 455 25–34 807 35–44 618 45–54 677 55–64 525 65–74 284 75–84 226 > 85 57 Level of urbanizationa 1 1095 2 967 3 579 4 454 5 554 Monthly income (US$) 1–530 1398 530–830 1162 ≥ 830 1089 Geographical regionb Northern 1767 Central 814 Southern 973 Eastern 95
(566) (434)
Comparison patients (n = 3649) 2066 (566) 1583 (434)
P-value > 100
(125) (221) (169) (186) (144) (78) (62) (16)
455 807 618 677 525 284 226 57
(125) (221) (169) (186) (144) (78) (62) (16)
> 100
(300) (265) (159) (124) (152)
1115 957 597 476 504
(306) (262) (164) (130) (138)
050
(383) (318) (298)
1348 (369) 1193 (327) 1108 (304)
048
(484) (223) (267) (26)
1798 809 959 83
075
(493) (222) (263) (23)
Values given as n (%). a1 = most urbanized, 5 = least urbanized. b In Tawian.
British Journal of Dermatology (2015) 172, pp1346–1352
Table 2 shows the use of health care resources in the 1year period following the index date for patients with psoriasis and those without. With regard to dermatology services, patients with psoriasis had significantly more outpatient visits (35 vs. 09; P < 001) and significantly higher outpatient costs (US$14800 vs. US$1220; P < 001) than comparison patients. This suggests that outpatient costs were about 121-fold greater for patients with psoriasis than for comparison patients. Furthermore, we found that total costs were greater for patients with psoriasis than for comparison patients (US$58160 vs. US$34720; P < 001). However, there was no significant difference in inpatient days or inpatient costs between patients with psoriasis and those without. With regard to nondermatology services, internal medicine, family medicine and Chinese medicine were the major outpatient services used by patients with or without psoriasis. Table 2 Use and costs of health care services within 1 year by patients with psoriasis and comparison patients
Variable
Patients with psoriasis (n = 3649)
Dermatology services Outpatient 35 visits (n) Outpatient 1480 costs (US$) Inpatient 19 days (n) Inpatient 4336 costs (US$) Total costs 5816 (US$) Nondermatology services Outpatient 213 visits (n) Outpatient 9046 costs (US$) Inpatient 18 days (n) Inpatient 4309 costs (US$) Total costs 13355 (US$) All health services Outpatient 248 visits (n) Outpatient 10526 costs (US$) Inpatient 37 days (n) Inpatient 8645 costs (US$) Total costs 19171 (US$)
Comparison patients (n = 3649)
P-value
09 27
< 001
6389
122 442
< 001
100
16 113
029
26621
3350 21435
008
27396
3472 21449 < 001
59
202 29699
176 177
< 001
6635 18041 < 001 16 113
035
26605
3349 21434
009
43423
9983 30616 < 001
99
217 30450 199 53222
185 182
< 001
6757 18068 < 001 32 226
032
6699 42869
009
65979 13456 49698 < 001
Values are given as mean SD.
© 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1349
Additionally, internal medicine, surgery, and obstetrics and gynaecology were commonly used inpatient services (data not shown). Table 2 shows that patients with psoriasis had significantly more outpatient visits (213 vs. 176; P < 001) and significantly higher outpatient costs (US$90460 vs. US $66350; P < 001) than comparison patients. Patients with psoriasis also incurred significantly higher total costs compared with comparison patients (US$13355 vs. US$9983; P < 001). However, the number of inpatient days (18 vs. 16) and inpatient costs of patients with psoriasis (US$43090 vs. US$33490) were not significantly higher than those of the comparison patients. With regard to overall health care service utilization, patients with psoriasis had significantly more outpatient visits (248 vs. 185; P < 001), and significantly higher outpatient (US$105260 vs. US$67570; P < 001) and total costs (US $191710 vs. US$134560; P < 001) than comparison patients. This indicates that total costs were about 14-fold greater for patients with psoriasis than comparison patients. The number of inpatient days (37 vs. 32) and inpatient costs of patients with psoriasis (US$86450 vs. US$66990) were not significantly higher than those of comparison patients. Table 3 shows the differences in health care service utilization between patients with other types of psoriasis and patients with psoriatic arthritis. With regard to the utilization of dermatology services, the number of outpatient visits, outpatient costs, number of inpatient days, inpatient costs and total costs were not significantly different between patients with psoriatic arthritis and patients with other types of psoriasis. With regard to the utilization of nondermatology services, patients with psoriatic arthritis had significantly more outpatient visits (261 vs. 211; P < 001), outpatient costs (US $182280 vs. US$85910; P < 001) and total costs (US $256420 vs. US$127470; P < 001) than patients with other types of psoriasis. However, the number of inpatient days (20 vs. 18) and inpatient costs (US$74140 vs. US$41560) were not significantly different from those of patients with other types of psoriasis. Furthermore, with regard to utilization of all health services, patients with psoriatic arthritis had significantly more outpatient visits (291 vs. 246; P < 001), and higher outpatient (US$205490 vs. US$100300; P < 001) and total costs (US$354670 vs. US$183650) compared with patients with other types of psoriasis. Table 4 shows the differences in the use of health care services between patients with moderate-to-severe psoriasis and those with mild psoriasis. With regard to the use of dermatology services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (71 vs. 29; P < 001), higher outpatient costs (US$58830 vs. US$7650; P < 001), more inpatient days (29 vs. 17; P = 002) and higher total costs (US$114440 vs. US$49020; P < 001) than patients with mild psoriasis. Similarly, with regard to nondermatology services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (254 vs. 206; P < 001), higher outpatient costs (US$139540 vs. US$82480; P < 001), more inpatient days (28 vs. 17; P = 003) and higher total © 2014 British Association of Dermatologists
Table 3 Use and costs of health care services within 1 year by patients with psoriatic arthritis and patients with psoriasis Patients with psoriatic arthritis (n = 172)
Variable
Dermatology services Outpatient 30 visits (n) Outpatient 2321 costs (US$) Inpatient 22 days (n) Inpatient 7505 costs (US$) Total costs 9825 (US$) Nondermatology services Outpatient 261 visits (n) Outpatient 18228 costs (US$) Inpatient 20 days (n) Inpatient 7414 costs (US$) Total costs 25642 (US$) All health services Outpatient 291 visits (n) Outpatient 20549 costs (US$) Inpatient 43 days (n) Inpatient 14918 costs (US$) Total 35467 costs (US$)
Patients with psoriasis (n = 3477)
P-value
35 59
022
1439 6200
023
18 101
062
41068
4179 25696
029
42564
5618 26415
020
57 9415 94
201 32694 92 41073
211 201
< 001
8591 29474 < 001 18 99
077
4156 25678
030
53749 12747 42765 < 001
210
246 217
001
33424 10030 30215 < 001 36 200
069
8335 51370
030
90534 18365 64433
002
185 82136
Values are given as mean SD.
costs (US$194260 vs. US$123690; P < 001) than patients with mild psoriasis. Additionally, with regard to the use of all health services, patients with moderate-to-severe psoriasis had significantly more outpatient visits (325 vs. 236; P < 001), higher outpatient costs (US$198370 vs. US$90130, P < 001), more inpatient days (57 vs. 34, P = 002) and higher total costs (US$30870 vs. US$17271; P < 001) than patients with mild psoriasis. Only inpatient costs for dermatology services, nondermatology services and all health services were not significantly different between patients with moderate-to-severe psoriasis and those with mild psoriasis.
Discussion This population-based study compared the use of medical services between patients with psoriasis and those without. We found that for dermatology services, patients with psoriasis British Journal of Dermatology (2015) 172, pp1346–1352
1350 Health care services use by patients with psoriasis, L.-T. Kao et al. Table 4 Use and costs of health care services within 1 year by patients with moderate-to-severe psoriasis and patients with mild psoriasis
Variable
Patients with moderate-to-severe Patients with mild psoriasis (n = 510) psoriasis (n = 3139) P-value
Dermatology services Outpatient 71 visits (n) Outpatient 5883 costs (US$) Inpatient 29 days (n) Inpatient 5561 costs (US$) Total costs 11444 (US$) Nondermatology services Outpatient 254 visits (n) Outpatient 13954 costs (US$) Inpatient 28 days (n) Inpatient 5472 costs (US$) Total costs 19426 (US$) All health services Outpatient 325 visits (n) Outpatient 19837 costs (US$) Inpatient 57 days (n) Inpatient 11033 costs (US$) Total costs 30870 (US$)
87 14612
29 50
< 001
765 3027
< 001
17 99
002
21986
4137 27298
019
26290
4902 27467
< 001
206 198
< 001
8248 29788
< 001
110
218 28685
17 97
003
21938
4121 27286
021
39076
12369 44015
< 001
236 210
< 001
9013 29995
< 001
108
241 31584
34 196
002
43910
8257 54582
020
57951
17271 67008
< 001
218
Values are given as mean SD.
had fourfold more outpatient visits (35 vs. 09) and 12-fold higher outpatient costs (US$14800 vs. US$1220) compared with patients without psoriasis. Moreover, for nondermatology services, patients with psoriasis had more outpatient visits and higher annual total costs than those without (213 vs. 176 and US$90460 vs. US$66350, respectively). The study demonstrated that patients in Taiwan with psoriasis utilized medical services more than those without. The majority of previous studies concentrated on the direct or indirect costs of psoriasis-associated treatments.8,10,11,14 Nevertheless, very few studies compared the use of health care services between patients with psoriasis and those without. In this study, we found that patients with psoriasis had more outpatient visits, and higher outpatient and total costs for both dermatology and nondermatology services than patients without psoriasis. This might be owing to the occurrence of comorbidities in patients with psoriasis, as the chronic British Journal of Dermatology (2015) 172, pp1346–1352
inflammatory feature of psoriasis has been suggested to be one of the potential risk factors for the progression of comorbidities.20 Several studies have reported that, compared with the general population, patients with psoriasis show a significantly increasing incidence of comorbidities such as arthritis, cardiovascular disease, metabolic syndrome, depressive disorder and so on.20–25 Furthermore, one U.S. study by Crown et al.26 showed that patients with psoriasis who had significantly more comorbidities incurred higher total annual health care costs than those without psoriasis. Therefore, the high incidence of comorbidities associated with psoriasis might explain the increased use of health care services among patients with psoriasis. Patients with psoriatic arthritis had significantly more outpatient visits (261 vs. 211), and higher outpatient and total costs (US$182280 vs. US$85910 and US$256420 vs. US $127470, respectively) for nondermatology services compared with patients with other types of psoriasis. This finding is consistent with a report by Kimball et al.,27 who concluded that patients with comorbidities such as cardiovascular disease, psoriatic arthritis, depression and so on needed to use health care services more often than patients without comorbidities. They also reported that patients with psoriasis who had any comorbidities used more health care resources (e.g. had higher hospitalization rates, more outpatient visits and higher 6-month mean costs of health care) than those with no comorbidities. However, our study showed that patients with psoriatic arthritis did not have significantly more outpatient visits or higher costs for dermatology services than those with other types of psoriasis. It may be that patients with psoriatic arthritis might visit rheumatology rather than dermatology. Moreover, our study found that the patients with moderateto-severe psoriasis had significantly more outpatient visits, higher outpatient costs, more inpatient days and higher total costs for dermatology services, nondermatology services and all health services compared with patients with mild psoriasis. These outcomes are consistent with previous studies that estimated economic burdens for patients with psoriasis.10,14 These studies found that expenses incurred for psoriasis were related to disease severity. The increasing use of dermatology services could be explained by the high costs and lengthy psoriasis treatment. In addition, the high use of nondermatology services might be owing to the likelihood of comorbidities. One study has reported that the burdens of comorbidities increase with rising disease severity among patients with psoriasis.28 Nevertheless, for both dermatology and nondermatology services, our study showed that there were no statistically significant differences in inpatient days and costs between patients with and without psoriasis and between patients with psoriatic arthritis and other types of psoriasis. This might suggest that the comorbidities of patients with psoriasis may not be severe enough to warrant hospitalization. The particular strength of this study is the use of a population-based dataset with a single-payer system and wide health benefit coverage in Taiwan. These characteristics could decrease the effect of a selection bias, provide an adequate © 2014 British Association of Dermatologists
Health care services use by patients with psoriasis, L.-T. Kao et al. 1351
sample size and increase the statistical power in identifying different health care service use rates between patients with psoriasis and those without. Moreover, this dataset recorded the total medical costs and utilization information for all study patients since they entered the healthcare system in Taiwan. These features of the dataset reduced the potential for recall bias in the study. Furthermore, most of the included patients in the study are Taiwanese. Prior studies that discuss health care service utilization in patients with psoriasis in Asian countries were lacking. Because psoriasis has a strong genetic component, our outcomes could be generalized to the Asian ethnic group worldwide.29 In addition, our study might be generalized to some countries, such as Canada, Germany, France, South Korea, Japan, the U.K., Sweden and so on as the healthcare systems in these countries have national/public health insurance, similar to the Taiwanese system.30–32 However, because the sources of health care finance, health care providers and insurance coverage rates are dissimilar in different healthcare systems, our study can be generalized cautiously to the countries that are involved in national health services or private insurance systems (e.g. the U.S.A.).31,32 Nevertheless, there are several limitations to our study. Firstly, the cost and utilization analyses in our study were based on records released by the NHI administration. Therefore, we could not evaluate costs if patients with psoriasis did not seek medical care. Additionally, we could not assess costs of over-the-counter drugs as they are not covered by the NHI programme. Secondly, we did not estimate indirect psoriasisassociated costs, such as the loss of productivity caused by absence from work, unemployment and occupational retraining. To our knowledge, there are no accessible records of indirect costs in Taiwan. Thirdly, the algorithm to identify the sensitivity and specificity of the selection of patients with psoriasis has not been previously validated in LHID. However, many previous studies have used this database to identify patients with psoriasis.33–35 Therefore, this method is well recognized in this field of research in Taiwan. We found that patients with psoriasis used health care services significantly more often than the comparison group. Moreover, this outcome was observed for both dermatology and nondermatology services. Patients with moderate-to-severe psoriasis also used health care services more often than patients with mild psoriasis. Our study objectively evaluated the economic burdens of patients with psoriasis. The results of this study may have some important policy implications for medical professionals and policy makers in terms of providing appropriate approaches that could eventually prove to be of significant benefit to the management of this chronic disease. Nevertheless, further studies are warranted to explore the factors contributing to the increased health care use by patients with psoriasis.
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