Research
Original Investigation
Costs of Care for Hospitalization for Pemphigus in the United States Derek Hsu, BA; Joaquin Brieva, MD; Jonathan I. Silverberg, MD, PhD, MPH Editorial IMPORTANCE Pemphigus is an autoimmune blistering disorder associated with significant
morbidity and mortality. However, little is known about the inpatient burden of pemphigus.
Supplemental content at jamadermatology.com
OBJECTIVE To determine the incidence of and risk factors for hospitalization with pemphigus and cost of care. DESIGN, SETTING, AND PARTICIPANTS The 2002-2012 Nationwide Inpatient Sample provided by the Healthcare Cost and Utilization Project from the Agency for Healthcare Research and Quality was analyzed. A total of 87 039 711 children and adults (mean [SD] age, 57.7 [0.98] years for those with a primary diagnosis of pemphigus; 70.6 [0.32] years for those with a secondary diagnosis of pemphigus; and 47.9 [0.19] years for those without a diagnosis of pemphigus) were studied. Data analysis was performed from June 1 to August 30, 2015. MAIN OUTCOMES AND MEASURES Hospitalization rates, length of stay, and cost of care. RESULTS There were 1185 and 5221 patients admitted with a primary or secondary diagnosis of pemphigus, respectively; when factoring in weights that generalize the sample to the entire hospitalized US cohort, these admissions represented weighted frequencies of 5647 and 24 880, respectively. In multivariable logistic regression models with stepwise selection, increasing age (adjusted odds ratios [95% CIs]: 18-39 years: 5.53 [4.28-7.14], P < .001; 40-59 years: 10.98 [8.46-14.24], P < .001; 60-79 years: 7.54 [5.75-9.89], P < .001; ⱖ80 years: 7.57 [5.71-10.04], P < .001), female sex (1.10 [1.01-1.20], P = .047), nonwhite race/ethnicity (black: 1.94 [1.75-2.14], P < .001; Hispanic: 4.10 [3.74-4.48], P < .001; Asian: 3.16 [2.68-3.73], P < .001; Native American: 2.11 [1.45-3.08], P < .001), lower household income (quartile 2: 1.19 [1.07-1.32], P < .001), being insured with Medicare (1.56 [1.41-1.74], P < .001) or Medicaid (1.55 [1.39-1.73], P < .001), number of chronic conditions (2-5: 2.36 [2.10-2.65], P < .001; ⱖ6: 1.47 [1.29-1.69], P < .001), hospital location in a metropolitan area (not metropolitan or micropolitan: 0.60 [0.49-0.72], P < .001), and summer season (1.12 [1.02-1.23], P = .02) were all associated with hospitalization for pemphigus. The total inflation-adjusted cost of care for patients with a primary inpatient diagnosis of pemphigus was $74 466 305, with a mean (SD) annual cost of $14 520.93 ($913.22). The inflation-adjusted cost of care for patients with a primary diagnosis of pemphigus increased significantly from 2002 to 2012 (analysis of variance, P < .001). In particular, length of stay was higher in racial/ethnic minorities compared with whites (survey linear regression, log β [95% CI]: black: 0.076 [0.075-0.076]; Hispanic: 0.021 [0.021-0.022]; Asian: 0.037 [0.036-0.039]; Native American: 0.010 [0.0076-0.013]), lower quartile household income (quartile 1: 0.024 [0.023-0.024]; quartile 2: 0.0029 [0.0022-0.0035]), and those without private insurance (Medicare: 0.12 [0.12-0.12]; Medicaid: 0.082 [0.081-0.083]; no charge: 0.051 [0.047-0.055]). CONCLUSIONS AND RELEVANCE There is a significant inpatient burden for pemphigus in the United States. Moreover, there appear to be racial/ethnic and health care disparities with respect to pemphigus, such that poor, nonwhite, and/or uninsured or underinsured patients have higher odds of hospitalization.
JAMA Dermatol. doi:10.1001/jamadermatol.2015.5240 Published online February 10, 2016.
Author Affiliations: Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Illinois (Hsu, Brieva); Departments of Dermatology, Preventive Medicine, and Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois (Silverberg). Corresponding Author: Jonathan I Silverberg, MD, PhD, MPH, Department of Dermatology, Northwestern University Feinberg School of Medicine, 676 N St Clair St, Ste 1600, Chicago, IL 60611 ([email protected]).
(Reprinted) E1
Copyright 2016 American Medical Association. All rights reserved.
Downloaded From: http://archderm.jamanetwork.com/ by a University of Pittsburgh User on 02/28/2016
Research Original Investigation
US Hospitalization Costs for Pemphigus
P
emphigus is a debilitating autoimmune disorder characterized by acantholytic blisters of the skin and mucous membranes. The incidence and prevalence of the variants of pemphigus are not completely known.1 Hospitalization of patients with pemphigus may occur from the intense pain, esophageal involvement leading to difficulty eating,2 increased opportunistic infections,3 medicationrelated complications, and/or comorbid autoimmune disorders associated with pemphigus.4 However, to our knowledge, few studies have evaluated the inpatient burden of pemphigus. Previous studies have found racial/ethnic and socioeconomic disparities in hospitalization rates and outcomes for stroke,5 cardiovascular disease,6 asthma,7 and acute respiratory illness.8 We hypothesized that pemphigus is also associated with similar racial/ethnic and socioeconomic disparities, possibly related to being underinsured and having less access to dermatologic care. In the present study, we analyzed the incidence of hospitalization, cost of care, and length of stay in US patients with pemphigus.
Methods Data Source The 2002-2012 Nationwide Inpatient Sample (NIS) provided by the Healthcare Cost and Utilization Project (HCUP) from the Agency for Healthcare Research and Quality was analyzed. Each year of the NIS contains an approximately 20% stratified representative sample of all inpatient hospitalizations in the United States. Sample weights were created by the NIS that factored the sampling design of hospitals in the United States. These sample weights are needed to provide representative estimates of hospital discharges across the whole country. Data analysis was performed from June 1 to August 30, 2015. All data were deidentified and no attempts were made to identify any of the individuals in the database. Patient consent was not obtained because all patient records were received deidentified. All parties with access to the HCUP were adherent to the HCUP’s formal data use agreement. The study was approved by the institutional review board at Northwestern University.
Identification of Pemphigus The databases were searched for a primary and/or secondary diagnosis of pemphigus using International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes. The primary diagnosis was defined in the NIS as the condition chiefly responsible for admission to the hospital for care. An ICD-9-CM code of 694.4 corresponds to pemphigus vulgaris, pemphigus vegetans, pemphigus foliaceous, pemphigus erythematosus, paraneoplastic pemphigus, and druginduced pemphigus. A previous study9 validated the use of a single ICD-9-CM code in the inpatient setting for the study of pemphigus. Patients with ICD-9-CM diagnostic codes of both 694.4 and 694.5 (bullous pemphigoid) were excluded.
Data Processing and Statistical Analysis All data analyses and statistical processes were performed using SAS statistical software, version 9.4 (SAS Institute Inc). AnalyE2
ses of survey responses were performed using SURVEY procedures. Weighted prevalences of hospitalization with a primary or secondary ICD-9-CM code of pemphigus were determined. The hospital cost for inpatient care was calculated based on the total charge of the hospitalization and the cost to charge ratio estimated by the HCUP. All costs were adjusted for inflation to the year 2014 according to the Consumer Price Index from the US Bureau of Labor Statistics.10 Summary statistics were generated for length of stay, total charge, and estimated inflation-adjusted cost of care, including sum, mean, SD, minimum, maximum, median, interquartile range, and range. The control group included all patients without any diagnosis of pemphigus, yielding a representative cohort of hospitalized patients in the United States. Analysis of variance was used to compare hospitalization rates for pemphigus over time. Post hoc comparisons were performed in 2004-2005, 20062007, 2008-2009, and 2010-2012 vs 2002-2003 using the Tukey method. To determine the predictors of hospitalization, we constructed survey-weighted binary logistic regression models with hospitalization for pemphigus as the dependent variable. To determine the predictors of cost of care and length of stay, we constructed linear regression models with log-transformed cost of care and length of stay as the dependent variables. Cost of care and length of stay were log transformed because they were not normally distributed. Other independent variables included age (0-17, 18-39, 40-59, 60-79, ≥80 years), sex (male, female), race/ethnicity (white, black, Hispanic, Asian, Native American, multiracial, or other), median annual income of the hospital zip code (quartiles), health insurance coverage (yes vs no; Medicare, Medicaid, private, selfpay, no charge, other), number of chronic conditions (0-1, 2-5, ≥6), season of admission (winter, spring, summer, autumn), hospital location (metropolitan areas [≥1 urban clusters of population ≥50 000] with ≥1 million people, fringe area or metropolitan area with
Original Investigation
Costs of Care for Hospitalization for Pemphigus in the United States Derek Hsu, BA; Joaquin Brieva, MD; Jonathan I. Silverberg, MD, PhD, MPH Editorial IMPORTANCE Pemphigus is an autoimmune blistering disorder associated with significant
morbidity and mortality. However, little is known about the inpatient burden of pemphigus.
Supplemental content at jamadermatology.com
OBJECTIVE To determine the incidence of and risk factors for hospitalization with pemphigus and cost of care. DESIGN, SETTING, AND PARTICIPANTS The 2002-2012 Nationwide Inpatient Sample provided by the Healthcare Cost and Utilization Project from the Agency for Healthcare Research and Quality was analyzed. A total of 87 039 711 children and adults (mean [SD] age, 57.7 [0.98] years for those with a primary diagnosis of pemphigus; 70.6 [0.32] years for those with a secondary diagnosis of pemphigus; and 47.9 [0.19] years for those without a diagnosis of pemphigus) were studied. Data analysis was performed from June 1 to August 30, 2015. MAIN OUTCOMES AND MEASURES Hospitalization rates, length of stay, and cost of care. RESULTS There were 1185 and 5221 patients admitted with a primary or secondary diagnosis of pemphigus, respectively; when factoring in weights that generalize the sample to the entire hospitalized US cohort, these admissions represented weighted frequencies of 5647 and 24 880, respectively. In multivariable logistic regression models with stepwise selection, increasing age (adjusted odds ratios [95% CIs]: 18-39 years: 5.53 [4.28-7.14], P < .001; 40-59 years: 10.98 [8.46-14.24], P < .001; 60-79 years: 7.54 [5.75-9.89], P < .001; ⱖ80 years: 7.57 [5.71-10.04], P < .001), female sex (1.10 [1.01-1.20], P = .047), nonwhite race/ethnicity (black: 1.94 [1.75-2.14], P < .001; Hispanic: 4.10 [3.74-4.48], P < .001; Asian: 3.16 [2.68-3.73], P < .001; Native American: 2.11 [1.45-3.08], P < .001), lower household income (quartile 2: 1.19 [1.07-1.32], P < .001), being insured with Medicare (1.56 [1.41-1.74], P < .001) or Medicaid (1.55 [1.39-1.73], P < .001), number of chronic conditions (2-5: 2.36 [2.10-2.65], P < .001; ⱖ6: 1.47 [1.29-1.69], P < .001), hospital location in a metropolitan area (not metropolitan or micropolitan: 0.60 [0.49-0.72], P < .001), and summer season (1.12 [1.02-1.23], P = .02) were all associated with hospitalization for pemphigus. The total inflation-adjusted cost of care for patients with a primary inpatient diagnosis of pemphigus was $74 466 305, with a mean (SD) annual cost of $14 520.93 ($913.22). The inflation-adjusted cost of care for patients with a primary diagnosis of pemphigus increased significantly from 2002 to 2012 (analysis of variance, P < .001). In particular, length of stay was higher in racial/ethnic minorities compared with whites (survey linear regression, log β [95% CI]: black: 0.076 [0.075-0.076]; Hispanic: 0.021 [0.021-0.022]; Asian: 0.037 [0.036-0.039]; Native American: 0.010 [0.0076-0.013]), lower quartile household income (quartile 1: 0.024 [0.023-0.024]; quartile 2: 0.0029 [0.0022-0.0035]), and those without private insurance (Medicare: 0.12 [0.12-0.12]; Medicaid: 0.082 [0.081-0.083]; no charge: 0.051 [0.047-0.055]). CONCLUSIONS AND RELEVANCE There is a significant inpatient burden for pemphigus in the United States. Moreover, there appear to be racial/ethnic and health care disparities with respect to pemphigus, such that poor, nonwhite, and/or uninsured or underinsured patients have higher odds of hospitalization.
JAMA Dermatol. doi:10.1001/jamadermatol.2015.5240 Published online February 10, 2016.
Author Affiliations: Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Illinois (Hsu, Brieva); Departments of Dermatology, Preventive Medicine, and Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois (Silverberg). Corresponding Author: Jonathan I Silverberg, MD, PhD, MPH, Department of Dermatology, Northwestern University Feinberg School of Medicine, 676 N St Clair St, Ste 1600, Chicago, IL 60611 ([email protected]).
(Reprinted) E1
Copyright 2016 American Medical Association. All rights reserved.
Downloaded From: http://archderm.jamanetwork.com/ by a University of Pittsburgh User on 02/28/2016
Research Original Investigation
US Hospitalization Costs for Pemphigus
P
emphigus is a debilitating autoimmune disorder characterized by acantholytic blisters of the skin and mucous membranes. The incidence and prevalence of the variants of pemphigus are not completely known.1 Hospitalization of patients with pemphigus may occur from the intense pain, esophageal involvement leading to difficulty eating,2 increased opportunistic infections,3 medicationrelated complications, and/or comorbid autoimmune disorders associated with pemphigus.4 However, to our knowledge, few studies have evaluated the inpatient burden of pemphigus. Previous studies have found racial/ethnic and socioeconomic disparities in hospitalization rates and outcomes for stroke,5 cardiovascular disease,6 asthma,7 and acute respiratory illness.8 We hypothesized that pemphigus is also associated with similar racial/ethnic and socioeconomic disparities, possibly related to being underinsured and having less access to dermatologic care. In the present study, we analyzed the incidence of hospitalization, cost of care, and length of stay in US patients with pemphigus.
Methods Data Source The 2002-2012 Nationwide Inpatient Sample (NIS) provided by the Healthcare Cost and Utilization Project (HCUP) from the Agency for Healthcare Research and Quality was analyzed. Each year of the NIS contains an approximately 20% stratified representative sample of all inpatient hospitalizations in the United States. Sample weights were created by the NIS that factored the sampling design of hospitals in the United States. These sample weights are needed to provide representative estimates of hospital discharges across the whole country. Data analysis was performed from June 1 to August 30, 2015. All data were deidentified and no attempts were made to identify any of the individuals in the database. Patient consent was not obtained because all patient records were received deidentified. All parties with access to the HCUP were adherent to the HCUP’s formal data use agreement. The study was approved by the institutional review board at Northwestern University.
Identification of Pemphigus The databases were searched for a primary and/or secondary diagnosis of pemphigus using International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes. The primary diagnosis was defined in the NIS as the condition chiefly responsible for admission to the hospital for care. An ICD-9-CM code of 694.4 corresponds to pemphigus vulgaris, pemphigus vegetans, pemphigus foliaceous, pemphigus erythematosus, paraneoplastic pemphigus, and druginduced pemphigus. A previous study9 validated the use of a single ICD-9-CM code in the inpatient setting for the study of pemphigus. Patients with ICD-9-CM diagnostic codes of both 694.4 and 694.5 (bullous pemphigoid) were excluded.
Data Processing and Statistical Analysis All data analyses and statistical processes were performed using SAS statistical software, version 9.4 (SAS Institute Inc). AnalyE2
ses of survey responses were performed using SURVEY procedures. Weighted prevalences of hospitalization with a primary or secondary ICD-9-CM code of pemphigus were determined. The hospital cost for inpatient care was calculated based on the total charge of the hospitalization and the cost to charge ratio estimated by the HCUP. All costs were adjusted for inflation to the year 2014 according to the Consumer Price Index from the US Bureau of Labor Statistics.10 Summary statistics were generated for length of stay, total charge, and estimated inflation-adjusted cost of care, including sum, mean, SD, minimum, maximum, median, interquartile range, and range. The control group included all patients without any diagnosis of pemphigus, yielding a representative cohort of hospitalized patients in the United States. Analysis of variance was used to compare hospitalization rates for pemphigus over time. Post hoc comparisons were performed in 2004-2005, 20062007, 2008-2009, and 2010-2012 vs 2002-2003 using the Tukey method. To determine the predictors of hospitalization, we constructed survey-weighted binary logistic regression models with hospitalization for pemphigus as the dependent variable. To determine the predictors of cost of care and length of stay, we constructed linear regression models with log-transformed cost of care and length of stay as the dependent variables. Cost of care and length of stay were log transformed because they were not normally distributed. Other independent variables included age (0-17, 18-39, 40-59, 60-79, ≥80 years), sex (male, female), race/ethnicity (white, black, Hispanic, Asian, Native American, multiracial, or other), median annual income of the hospital zip code (quartiles), health insurance coverage (yes vs no; Medicare, Medicaid, private, selfpay, no charge, other), number of chronic conditions (0-1, 2-5, ≥6), season of admission (winter, spring, summer, autumn), hospital location (metropolitan areas [≥1 urban clusters of population ≥50 000] with ≥1 million people, fringe area or metropolitan area with
