Scand J Urol Nephrol26: 257-263, 1992
COST EFFECTIVENESS OF EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY AND PERCUTANEOUS NEPHROLITHOTOMY FOR MEDIUM-SIZED KIDNEY STONES A Randomised Clinical Trial
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Per Carlsson,' Anne-Charlotte K i n q 2 Hans-Goran Tiselius,3 Hans OhlsCn4and Mikael Rahmqvist' From the 'Center for Medical Technology Assessment, Linkoping University, 'Department of Urology, St Gorans Hospital, Stockholm, 'Department of Urology, University Hospital, Linkoping and 4Department of Diagnostic Radiology, Karolinska Hospital, Stockholm, Sweden (Submitted September 18, 1991. Accepted for publication September 18, 1991)
Abstract. To evaluate percutaneous nephrolithotomy (PNL) and extracorporeal shock wave lithotripsy (ESWL) for their clinical effects, their cost effectiveness, their complication rates, and the patients' experiences, 55 consecutive patients were randomised to have one or other operation between October 1986 and October 1988. Six patients were excluded, 21 were treated with PNL and 28 with ESWL as primary treatment. Mean hospital stay and length of treatment were longer for PNL than for ESWL. Since I July 1987 all patients having ESWL have been treated without anaesthesia (n= IS), whereas epidural anaesthesia was used for all PNL. Slightly more of the ESWL patients experienced some pain during treatment. Minor complications or pain were more common after ESWL during the first 10 days after discharge from hospital. If patients with stone fragments of 4 mm or less were regarded as having a successful outcome, the success rates after one year were 94% for PNL and 77% for ESWL. The overall total cost was lower for ESWL than for PNL. the cost per successfully treated patient being f2172 for PNL and f1810 for ESWL. Medium sized kidney stones (6-30 mm, or 2-3 stones of 20 mm or less) can be efficiently and cheaply treated by both PNL and ESWL, though the cost of ESWL is lower. Even if effects other than cost (such as complications and patients' experience) are borne in mind, ESWL was superior to PNL for this group of patients.
Percutaneous nephrolithotomy (PNL) and extracorporeal shock wave lithotripsy (ESWL) have replaced open surgery for small and medium-sized kidney stones, and ureteric stones, and the two procedures have been widely adopted in most countries in western Europe and in the USA. There are, however, differences in the way the methods have been devel-
oped in these countries-for example in 1989 the number of lithotripters/million in the United Kingdom was 0.26, compared with 1.3 in Spain (9,a difference which reflects the fact that the choice of management of renal stones is still under debate. The uncertainty is partly because of the lack of controlled clinical trials and comprehensive assessments of the different methods. N o randomised clinical trial has so far been conducted to assess the relative success rates, complications, recovery times, or costs of treatment. Two previous comparisons of patients treated by PNL and ESWL (4,6) showed no differences in cost between the two procedures, but the figures were invalidated by large differences in both numbers of patients and their stone burdens. Aronne et al. (1) who used a retrospective cohort design to compare 29 matched pairs of patients treated by PNL and ESWL found no differences between the groups with regard to demographic data or stone burden. All patients with complicated stones were excluded. The ESWL group stayed in hospital for less time, and had fewer complications, and required fewer additional procedures than the PNL patients. The total charges were lower for ESWL. The problems with the study of Aronne et al. were that the only patients that were included were those with small stones that could be dealt with by a single ESWL treatment, and that the economic calculation was based on charges instead of real costs. Scand J Urol Nc>phrol26
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258
P. Carlsson et al.
A clinical comparison in the UK between 928 patients treated by ESWL or a combination of ESWL and PNL/ureteroscopy, and 195 similar patients treated by PNL alone, showed that after PNL significantly more patients were free of stones than after ESWL but their mean stay in hospital was longer (7). When the costs of the two methods were related to the number of patients free of stones after three months, ESWL was twice as expensive as PNL. Selection bias and the short study period restricted the value of this analysis. In Sweden 300 consecutive patients treated by ESWL in Linkoping were compared with 300 consecutive patients treated by PNL in Gothenburg (2). More became free of stones after PNL than after ESWL, but if patients with fragments less than 5 mm in diameter (which readily pass spontaneously) are considered to have been satisfactorily treated, the difference becomes small. The cost of each successfully treated and stone-free patient was much higher with ESWL for stones of more than 20 mm in diameter but was similar for ESWL and PNL when ureteric stones or stones smaller than 20 mm were treated. ESWL was associated with fewer and less severe complications than PNL. In that study ESWL was recommended for stones up to a diameter of 2-3 cm. The aim of the present randomized, prospective, study was to evaluate the medhods for their effects on: the cost of health care, complication rates, and patients' experiences, during one year.
Table 1. Comparability of groups. Figures are expressed as number ofpatients unless otherwise stated
Menlwomen Mean age (years) Stone category* A ( I stone < 5 mm) B ( 1 stone 6-20 mm or 2-3 < 10 mm) C ( 1 stone 21-30 mm, 2-3 < 20 mm, or > 4 < 10 mm) D ( I stone 2 3 1 mm, 2-3 > 20 mm, or > 4 > II mm) Mean number of stonedpatient Mean size of largest stone (mm) Range (mm) Mean outpatient attendances during past year
Previous stone disease Previous operation Patients with multiple stones Use of stone prevention drug Symptoms N o symptoms D";..
1 ail1
Infection Haematuria Bacteriuria
PNL (n=21)
ESWL (n=28)
1219 48.2
2018 49.0
0
1
19
20
1
I
1 2.8 12 7-2 5
2.9
-
3.4 13 5-27 2.1
Number of patients/ number of valid cases 17/19 26/27 7/19 6/27 511 7 12/28 3/19 7/27 6/19 11/19 2/19 2/19 6/19
2/16 10116 6/16 6/16 7/25
One patient in the PNL group and 5 in the ESWL group had bilaterial stones. Of these 4 were treated bilaterally. * According to Tiselius et al. (9).
PATIENTS AND METHODS ESWL was introduced in Sweden in 1985 at a time when PNL had been in limited use for four years. A natural consequence of the simultaneous appearance of two therapeutic techniques in urology was a need for a Swedish comparative study of their cost-effectiveness. It was not feasible to randomise half the patients in the county in which the first lithotripter was located, because the investment was considerable and particularly as the new technology had been well publicised. Instead, we explored the possibility of randomising patients in hospitals with experience of PNL, because for them it was a realistic choice, and five departments agreed to participate. PNL was done locally and ESWL at the main centre. Three hospitals never started to randomise patients for various reasons, including economic and technical, and for fear of losing patients. In addition, the Scand J Urol Nephrol26
number of randomised patients from one hospital was too small to be analysed. Finally 55 consecutive patients from one single hospital, the Karolinska Hospital, Stockholm, met the inclusion criteria - that is, stones of 4-30 mm in diameter and eligible for either ESWL or PNL. Of these patients 25 were randomised to have PNL at the Karolinska Hospital and 30 to have ESWL at Linkoping University Hospital. Four patients in the PNL group did not have an operation and were therefore excluded (two passed their stones naturally, one moved to another area, and one preferred to have ESWL). In the ESWL group one patient became pregnant and one developed malignant disease. A total of 28 patients were therefore treated with ESWL and 21 with PNL (Table I). There were more men in the ESWL group, but there
Randomized comparison of ES WL and percutaneous nephrolithotomy Table 11. Mean (SO) duration of treatment and length of stay in hospital
Duration of treatment (min) Length of hospital stay (days)
PNL (n=21)
ESWL (n=28)
79* (40.6)
43**( 13.8)
7.4 (4.5)
4.1 (2.6)
* Including one ESWL (95 min and 13 days) and one Scand J Urol Nephrol Downloaded from informahealthcare.com by Nyu Medical Center on 02/20/15 For personal use only.
ureterolithotomy (60 min) in 2 patients that failed.
** Including two PNL operations that failed of 65 min and 80 min, respectively. was no difference in mean age between the groups. There were more category C patients (Table I ) in the ESWL group than in the PNL group. One patient in the PNL group had a stone in category D. Slightly more patients in the ESWL group had had infections and haematuria, and two in the PNL group had hydrocalycosis and dysplasia, respectively.
Data collection Data were recorded throughout the whole treatment on seven different forms: 1. History of stone disease. 2. Stone characteristics as shown on radiography. 3. Clinical examination on admission. 4. The treatment protocol. 5. Patient diary I, completed during stay in hospital. 6. Patient diary 11, completed during the first 10 days after discharge. 7. Follow-up records after four weeks, six months and one year. Although the patients randomised to PNL were treated in Stockholm, all direct costs were calculated from the internal accounts in Linkoping during 1988 to avoid differences between the two groups that could be explained solely by differences in prices between the two hospitals involved. The costs were expressed in 1988 years’ prices converted into pounds sterling (SEK 1 = E0.095). All capital and running costs of ESWL were charged to a single account and separated into costs of treatment and costs for each day spent before and after treatment. The depreciation period for the lithotripter has been extended once, from 5 to 8 years, after a new assessment of the expected length of its economic life. The estimated cost of the Dornier HM3 lithotripter in 1988 was El98 020, which was 21% of the total cost of the ESWL treatment unit. Other important costs were salaries (including urologists 12 Yo), and equipment (including electrodes l6Y0, and radiographs 19%). The total cost of f 9 6 3 096 was distributed over 1096 treatments, which is equivalent to €879/treatment. The total cost for ESWL during 1988 was then divided by the total number of “treatment minutes”, giving a cost/minute I8 - 928263
259
of f 2 1 ; the corresponding cost/minute for the surgical theatre at the Linkoping Hospital was & I I . All patients for ESWL were admitted to a special ward at a daily cost of f 1 2 1 , which was lower than that on the regular urology ward ( E l 57). The cost for each patient was calculated from the accumulated treatment time and the number of inpatient days. Indirect costs such as travel were not included in the analysis.
Management of patients PNL was done under epidural anaesthesia in the department of diagnostic radiology with the collaboration of a radiologist and a urologist. A nephrostomy was made with the patient prone, and the track was dilated to 27 French scale. The nephroscope was introduced and the stone was usually extracted with forceps under fluoroscopic control. Ultrasonic disintegration was used for stones larger than 15 mm. A Nelaton catheter 20 French scale was used for nephrostomy, often with a coaxial pigtail catheter to keep it in place. The catheters were removed on the following day if radiographic examination showed no residual calculi. If residual stones were found, a second PNL was done. In some patients with gross haematuria or fever the nephrostomy catheter was kept in for another day. Patients were usually discharged the day after removal of the catheter. All ESWL treatments were carried out at Linkoping University Hospital using an unmodified Dornier HM-3 lithotripter. After 1 July, 1987 all patients (n= 15) were treated without anaesthesia; this was possible thanks to a voltage reduction to 14-16 kV and premedication with pethidine (75 mg) and diaze-
Table 111. Patients’ experience of the treatment PNL ( n = 17)
Duration of treatment Very tedious Rather tedious Indifferent Brief Pain during treatment Severe Moderate Little None Overall perception of treatment Frightening Unpleasant Rather unpleasant Not unpleasant
ESWL (n=25)
3
1
3 9 2
0 12 12
0 2 4 11
0 3 5 9
1
9 6 9
0 2 12 11
Data are missing for 4 and 3 patients respectively in each group. Scand J Urn1 Nephrol26
260
P. Carlsson et al.
Table IV. Post-treatment pain, use of analgesics, and fever while in hospital
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Day 1
Day 3
Day 5
PNL (n=18)
ESWL (n=25)
PNL (n=15)
ESWL (n=9)
PNL (n=10)
ESWL (n=4)
Pain Severe Moderate Little None
5 4 3 6
4
1 5
0
3 1 5
2
6
1 2 0 6
1
9 4 8
Analgesics Yes No
15 3
12 13
5 10
4
4 6
3
5
Fever ( > 38'C)' Yes No
1
16
0 25
9 15
2 7
0 10
0 4
a
3
1
1
1
One patient in the PNL group is missing.
pam (5 mg) given intramuscularly 30 min before treatment (8).
RESULTS Both mean treatment time and mean hospital stay were nearly twice as long for PNL as for ESWL. The range was greater in the PNL group (Table 11). Epidural anaesthesia was used for all PNL. One patient who required ureteroscopy and an-
other who required ureterolithotomy were given general anaesthesia. Roughly half the patients given ESWL were treated before the introduction of the anaesthetic-free procedure, and epidural (n=2) or spinal (n= 1) anaesthesia were used for them. Of 16 patients who responded satisfactorily to PNL, five were off work for a mean of 13.2 days between discharge and the first follow-up examination after four weeks. Only two of the
Table V. Pain, use of analgesics, and complications during the first nine days afer treatment Results expressed as percentage of group Day 3
Day 1
Day 5
PNL (n=18)
ESWL (n=24)
PNL (n= 18)
ESWL (n=23)
PNL ( n = 18)
ESWL (n=23)
YO
YO
YO
OO /
010
YO
Pain Nocturnal Persistent Used analgesics
7 28 6
29 38 29
22 22 6
13 30 22
11 11 11
13 17 17
Complications Hernaturia Fever (over 38°C)
28 6
26 8
6 6
14 4
16 11
17
Activities restricted
33
20
33
13
17
9
Scand J Urol Nephrol26
4
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Randomized comparison of ES W L and percutaneous nephrolithotomy 21 patients who responded well to ESWL took time off work (8 and 28 days, respectively). Patients' experience of the treatment is summarised in Table 111. There were only slight differences between the two groups. PNL generally took longer than ESWL, and consequently more patients in the PNL group found the operation tedious. On the other hand, slightly more patients undergoing ESWL had some degree of pain during treatment. and more in the PNL group found the treatment unpleasant. The PNL patients experienced further pain in hospital shortly after treatment, but the difference between the groups disappeared after five days (Table IV). Complications after treatment were more common after ESWL during the first 10 days after discharge, because of passage of fragments in the urine (Table V). More of the patients in the ESWL group experienced pain, but their pain did not restrict their normal daily activities any more than did the effects of PNL.
Clinical complications In the PNL group there was one case of septicaemia, one patient had a leaking nephrostomy catheter, one developed paralytic ileus because of leakage of fluid and there was one minor perforation of the renal pelvis. Among the ESWL patients one developed fever and one nausea and pain; three developed cutaneous haematomas probably as a result of the large number of shock waves used.
Day 9
Day 7 PNL (n=18)
PNL ( n = 18)
ESWL
(n=23)
YO
YO
YO
YO
ESWL
26 1
The results of treatment are summarised in Table VI.
Effectiveness of the treatment In the ESWL group six patients had residual stones of more than 5 mm in diameter after 12 months compared with one in the PNL group. Of these six, five had stones smaller than 8 mm. If patients with stone fragments of 5 mm or less (fragments that might easily pass spontaneously) are regarded as having had a successful outcome, the success rates after one year became 94% for PNL and 77% for ESWL. Symptoms In the PNL group there were 15 patients whose symptomatic responses were maintained at 12 months; 14 of these were completely free from symptoms (93 O/o) and one had had an infection with fever. In the ESWL group 19 of 2 1 patients were symptom free (91 O/O); one had some pain and one had pain, haematuria, and fever. Cost The mean total cost of El394 (range &68846420)/patient for ESWL was significantly lower than E2063 (range E763-$301 l)/patient for PNL (Table VII). The difference was even greater in a subgroup who had stones less than 2 cm in diameter. The cost/successfully treated patient after 12 months was E2196 for PNL and El810 for ESWL. The relatively low cost for ESWL is partly explained by the large turnover of patients at this particular centre. On the other hand, if ESWL is restricted to a small number of centres the travelling costs will be higher than if more lithotripters are used.
(n=23)
DISCUSSION 0 6 6
22 22
0 6 6
22 22
6 0
9 0
0 0
13 0
I1
13
11
9
17
13
Challah & Mays have discussed several factors that could make it difficult to mount a randomised trial (3), and the present study was only partly successful. The most important reasons for not taking part were fear of losing patients, budget restrictions, and lack of experience in PNL. The study is consequently relatively small, but the patients are comparable with regard to both stone classification and clinical history. We therefore think that the series was Scand J C'rol Nephrol 26
262
P. Carlsson et al.
Table VI. Number ofpatients free of stones afer four weeks and afer a year Four weeks
One year
PNL
PNL ESWL (n= 19) (n=26)
ESWL
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(n= 15) (n=25)
Free of stone Fragments < 5 mm Stones
11
8
15
11
4
11
3
9
> 5 mm
0 15
6 25
1
6 26
Total
19
big enough to allow valid conclusions to be drawn. The patient characteristics and results were, with a few exceptions, consistent with the previous findings in the Linkoping-Gothenburg study (2). The mean treatment time for category B stones changed from 123 min for PNL and 41 for ESWL in the Linkoping-Gothenburg study, to 79 and 43 min, respectively, in the present study (2), probably as a result of differences in technique-for example, endoscopic control was seldom used at the Karolinska Hospital. The mean hospital stay for ESWL did not change between the two studies, but the inpatient stay for PNL was shorter in the present study. The number of successfully treated patients was slightly higher in the Linkoping-Gothenburg study, 98 O/o of the PNL patients being free of stones after three months compared with 94% after six months in this study. The corresponding figures for ESWL were 87% (after four months) and 77% (after 12 months), respectively. We must emphasise that patients with residual fragments larger than 5 mm should be recommended to have a second session of ESWL, but for several reasons this was not done in the present study. It would have increased the cost, but would undoubtedly had resulted in a higher rate of stone-free patients. In the Linkoping-Gothenburg study the total cost/patient was rather lower for PNL, because the calculations were based on 1986 prices. The cost of ESWL dropped sharply between 1986 Scand J Urol Nephrol26
and 1988 because of the introduction of anaesthetic-free treatment in 1987, reduced expenditure for maintenance and electrodes, and an increase in the number of treatments given. The ESWL unit started operating in April 1985. During its second year in use (April 1986-March 1987) 846 treatments were carried out; during the period April 1988 - March 1989 this figure had risen to 1132. In the present study we assessed ESWL and PNL treatment of kidney stones from a number of aspects. In accordance with previous reports the results show that PNL results in a larger number of stone-free patients, an improvement that is, however, associated with higher costs both for the patient and for the health care system. In addition, the PNL patients had slightly more pain immediately after treatment, and had to stay in hospital longer. In contrast during the first 10 days at home, more ESWL patients had pain, possibly as a result of passage of stone fragments, but in the PNL group more patients perceived themselves restricted in daily activities and reported a significantly higher number of days off work. In the long term there was no difference in the length of time patients were free of symptoms. The disadvantage of referral to an ESWL centre a long way from home is of course difficult to evaluate in individual cases. There were only minor complications in both groups, though they were slightly more serious after PNL. The cost of treatment was significantly lower for ESWL, and as the Dornier HM-
Table VII. Total costs per patient (f) PNL
ESWL
P
AN patients
Number of
patients 21 Mean (SD) cost (E) 2 063 (1 31 5 ) Category B stones Number of patients 19 Mean (SD) cost (f) 2 061 ( 1 238)
28 1 394 (844)
>0.05
20 1 152 (231)
>0.003
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Randomized comparison of ES WL and percutaneous nephrolithotomy
3 was used, the current reduction in cost of electrodes indicates that the difference in costs will increase with time. The need for inpatient care after ESWL treatment is controversial. At some centres patients with small stones are treated as outpatients. In our study the mean hospital stay in a ward with less staff than the regular urology ward was 4.1 days including the day of treatment. One reason for the choice of inpatient treatment was to standardise the management of patients in the ESWL unit. This routine facilitates a high patient turnover, which reduces the costshession. We think that the possible reduction in total cost by treating some patients as outpatients is relatively small. We conclude that medium sized kidney stones (6-30 mm, or 2-3 stones less or equal to 20 mm) can be efficiently and cheaply treated by both PNL and ESWL, significantly lower. Even if effects other than cost (such as complications and patients’ experience) are borne in mind, ESWL is superior to PNL for this group of patients. REFERENCES 1. Aronne LJ, Braham RL, Richte R, Vaughan DE,
Ruchlin HS. Cost-effectiveness of extracorporeal shock-wave lithotripsy. Endourology 1988; 3 1 : 225-230.
263
2. Carlsson P, NauclCr J, Petterson S, Tiselius H-G. A cost-effectiveness analysis of extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy. Scand J Urol Nephrol 1989; Suppl. 122. 3. Challah S, Mays NB. The randomised controlled trial in the evaluation of new technology: a case study. Br Med J 1986; 292: 877-878. 4. Chang CR, Webb DR, Payne SR, Wickham JEA. Comparison of treatment of renal calculi by open surgery, percutaneous nephrolithotomy, and extracorporeal shockwave lithotripsy. Br Med J 1986; 292: 879-882. 5. Kirchberger S. The diffusion of two technologies for renal stone treatment across Europe. London: King’s Fund Centre for Health Services Development, 1991. 6. Lingeman JE, Saywell RM, Woods JR, Newman DM. Cost analysis of extracorporeal shock wave lithotripsy relative to other surgical and non-surgical treatment alternatives for urolithiasis. Med Care 1986; 24: 1151-1160. 7. Mays N, Challah S, Patel S, Palfrey E, Creeser R, Vadera P, Burey P. Clinical comparison of extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy in treating renal calculi. Br Med J 1988; 297: 253-258. 8. Petterson B. Extracorporeal shock wave lithotripsy of renal and ureteral stones-studies on indications, methods and results. Linkoping University Medical Dissertations No 293, 1989. 9. Tiselius H-G, Petterson B, Hellgren E, Carlsson P. Classification of patients subjected to extracorporeal shock wave lithotripsy. Scand J Urol Nephrol 1988; 22: 65-70.
Scand J Urol Nephrol26
COST EFFECTIVENESS OF EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY AND PERCUTANEOUS NEPHROLITHOTOMY FOR MEDIUM-SIZED KIDNEY STONES A Randomised Clinical Trial
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Per Carlsson,' Anne-Charlotte K i n q 2 Hans-Goran Tiselius,3 Hans OhlsCn4and Mikael Rahmqvist' From the 'Center for Medical Technology Assessment, Linkoping University, 'Department of Urology, St Gorans Hospital, Stockholm, 'Department of Urology, University Hospital, Linkoping and 4Department of Diagnostic Radiology, Karolinska Hospital, Stockholm, Sweden (Submitted September 18, 1991. Accepted for publication September 18, 1991)
Abstract. To evaluate percutaneous nephrolithotomy (PNL) and extracorporeal shock wave lithotripsy (ESWL) for their clinical effects, their cost effectiveness, their complication rates, and the patients' experiences, 55 consecutive patients were randomised to have one or other operation between October 1986 and October 1988. Six patients were excluded, 21 were treated with PNL and 28 with ESWL as primary treatment. Mean hospital stay and length of treatment were longer for PNL than for ESWL. Since I July 1987 all patients having ESWL have been treated without anaesthesia (n= IS), whereas epidural anaesthesia was used for all PNL. Slightly more of the ESWL patients experienced some pain during treatment. Minor complications or pain were more common after ESWL during the first 10 days after discharge from hospital. If patients with stone fragments of 4 mm or less were regarded as having a successful outcome, the success rates after one year were 94% for PNL and 77% for ESWL. The overall total cost was lower for ESWL than for PNL. the cost per successfully treated patient being f2172 for PNL and f1810 for ESWL. Medium sized kidney stones (6-30 mm, or 2-3 stones of 20 mm or less) can be efficiently and cheaply treated by both PNL and ESWL, though the cost of ESWL is lower. Even if effects other than cost (such as complications and patients' experience) are borne in mind, ESWL was superior to PNL for this group of patients.
Percutaneous nephrolithotomy (PNL) and extracorporeal shock wave lithotripsy (ESWL) have replaced open surgery for small and medium-sized kidney stones, and ureteric stones, and the two procedures have been widely adopted in most countries in western Europe and in the USA. There are, however, differences in the way the methods have been devel-
oped in these countries-for example in 1989 the number of lithotripters/million in the United Kingdom was 0.26, compared with 1.3 in Spain (9,a difference which reflects the fact that the choice of management of renal stones is still under debate. The uncertainty is partly because of the lack of controlled clinical trials and comprehensive assessments of the different methods. N o randomised clinical trial has so far been conducted to assess the relative success rates, complications, recovery times, or costs of treatment. Two previous comparisons of patients treated by PNL and ESWL (4,6) showed no differences in cost between the two procedures, but the figures were invalidated by large differences in both numbers of patients and their stone burdens. Aronne et al. (1) who used a retrospective cohort design to compare 29 matched pairs of patients treated by PNL and ESWL found no differences between the groups with regard to demographic data or stone burden. All patients with complicated stones were excluded. The ESWL group stayed in hospital for less time, and had fewer complications, and required fewer additional procedures than the PNL patients. The total charges were lower for ESWL. The problems with the study of Aronne et al. were that the only patients that were included were those with small stones that could be dealt with by a single ESWL treatment, and that the economic calculation was based on charges instead of real costs. Scand J Urol Nc>phrol26
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258
P. Carlsson et al.
A clinical comparison in the UK between 928 patients treated by ESWL or a combination of ESWL and PNL/ureteroscopy, and 195 similar patients treated by PNL alone, showed that after PNL significantly more patients were free of stones than after ESWL but their mean stay in hospital was longer (7). When the costs of the two methods were related to the number of patients free of stones after three months, ESWL was twice as expensive as PNL. Selection bias and the short study period restricted the value of this analysis. In Sweden 300 consecutive patients treated by ESWL in Linkoping were compared with 300 consecutive patients treated by PNL in Gothenburg (2). More became free of stones after PNL than after ESWL, but if patients with fragments less than 5 mm in diameter (which readily pass spontaneously) are considered to have been satisfactorily treated, the difference becomes small. The cost of each successfully treated and stone-free patient was much higher with ESWL for stones of more than 20 mm in diameter but was similar for ESWL and PNL when ureteric stones or stones smaller than 20 mm were treated. ESWL was associated with fewer and less severe complications than PNL. In that study ESWL was recommended for stones up to a diameter of 2-3 cm. The aim of the present randomized, prospective, study was to evaluate the medhods for their effects on: the cost of health care, complication rates, and patients' experiences, during one year.
Table 1. Comparability of groups. Figures are expressed as number ofpatients unless otherwise stated
Menlwomen Mean age (years) Stone category* A ( I stone < 5 mm) B ( 1 stone 6-20 mm or 2-3 < 10 mm) C ( 1 stone 21-30 mm, 2-3 < 20 mm, or > 4 < 10 mm) D ( I stone 2 3 1 mm, 2-3 > 20 mm, or > 4 > II mm) Mean number of stonedpatient Mean size of largest stone (mm) Range (mm) Mean outpatient attendances during past year
Previous stone disease Previous operation Patients with multiple stones Use of stone prevention drug Symptoms N o symptoms D";..
1 ail1
Infection Haematuria Bacteriuria
PNL (n=21)
ESWL (n=28)
1219 48.2
2018 49.0
0
1
19
20
1
I
1 2.8 12 7-2 5
2.9
-
3.4 13 5-27 2.1
Number of patients/ number of valid cases 17/19 26/27 7/19 6/27 511 7 12/28 3/19 7/27 6/19 11/19 2/19 2/19 6/19
2/16 10116 6/16 6/16 7/25
One patient in the PNL group and 5 in the ESWL group had bilaterial stones. Of these 4 were treated bilaterally. * According to Tiselius et al. (9).
PATIENTS AND METHODS ESWL was introduced in Sweden in 1985 at a time when PNL had been in limited use for four years. A natural consequence of the simultaneous appearance of two therapeutic techniques in urology was a need for a Swedish comparative study of their cost-effectiveness. It was not feasible to randomise half the patients in the county in which the first lithotripter was located, because the investment was considerable and particularly as the new technology had been well publicised. Instead, we explored the possibility of randomising patients in hospitals with experience of PNL, because for them it was a realistic choice, and five departments agreed to participate. PNL was done locally and ESWL at the main centre. Three hospitals never started to randomise patients for various reasons, including economic and technical, and for fear of losing patients. In addition, the Scand J Urol Nephrol26
number of randomised patients from one hospital was too small to be analysed. Finally 55 consecutive patients from one single hospital, the Karolinska Hospital, Stockholm, met the inclusion criteria - that is, stones of 4-30 mm in diameter and eligible for either ESWL or PNL. Of these patients 25 were randomised to have PNL at the Karolinska Hospital and 30 to have ESWL at Linkoping University Hospital. Four patients in the PNL group did not have an operation and were therefore excluded (two passed their stones naturally, one moved to another area, and one preferred to have ESWL). In the ESWL group one patient became pregnant and one developed malignant disease. A total of 28 patients were therefore treated with ESWL and 21 with PNL (Table I). There were more men in the ESWL group, but there
Randomized comparison of ES WL and percutaneous nephrolithotomy Table 11. Mean (SO) duration of treatment and length of stay in hospital
Duration of treatment (min) Length of hospital stay (days)
PNL (n=21)
ESWL (n=28)
79* (40.6)
43**( 13.8)
7.4 (4.5)
4.1 (2.6)
* Including one ESWL (95 min and 13 days) and one Scand J Urol Nephrol Downloaded from informahealthcare.com by Nyu Medical Center on 02/20/15 For personal use only.
ureterolithotomy (60 min) in 2 patients that failed.
** Including two PNL operations that failed of 65 min and 80 min, respectively. was no difference in mean age between the groups. There were more category C patients (Table I ) in the ESWL group than in the PNL group. One patient in the PNL group had a stone in category D. Slightly more patients in the ESWL group had had infections and haematuria, and two in the PNL group had hydrocalycosis and dysplasia, respectively.
Data collection Data were recorded throughout the whole treatment on seven different forms: 1. History of stone disease. 2. Stone characteristics as shown on radiography. 3. Clinical examination on admission. 4. The treatment protocol. 5. Patient diary I, completed during stay in hospital. 6. Patient diary 11, completed during the first 10 days after discharge. 7. Follow-up records after four weeks, six months and one year. Although the patients randomised to PNL were treated in Stockholm, all direct costs were calculated from the internal accounts in Linkoping during 1988 to avoid differences between the two groups that could be explained solely by differences in prices between the two hospitals involved. The costs were expressed in 1988 years’ prices converted into pounds sterling (SEK 1 = E0.095). All capital and running costs of ESWL were charged to a single account and separated into costs of treatment and costs for each day spent before and after treatment. The depreciation period for the lithotripter has been extended once, from 5 to 8 years, after a new assessment of the expected length of its economic life. The estimated cost of the Dornier HM3 lithotripter in 1988 was El98 020, which was 21% of the total cost of the ESWL treatment unit. Other important costs were salaries (including urologists 12 Yo), and equipment (including electrodes l6Y0, and radiographs 19%). The total cost of f 9 6 3 096 was distributed over 1096 treatments, which is equivalent to €879/treatment. The total cost for ESWL during 1988 was then divided by the total number of “treatment minutes”, giving a cost/minute I8 - 928263
259
of f 2 1 ; the corresponding cost/minute for the surgical theatre at the Linkoping Hospital was & I I . All patients for ESWL were admitted to a special ward at a daily cost of f 1 2 1 , which was lower than that on the regular urology ward ( E l 57). The cost for each patient was calculated from the accumulated treatment time and the number of inpatient days. Indirect costs such as travel were not included in the analysis.
Management of patients PNL was done under epidural anaesthesia in the department of diagnostic radiology with the collaboration of a radiologist and a urologist. A nephrostomy was made with the patient prone, and the track was dilated to 27 French scale. The nephroscope was introduced and the stone was usually extracted with forceps under fluoroscopic control. Ultrasonic disintegration was used for stones larger than 15 mm. A Nelaton catheter 20 French scale was used for nephrostomy, often with a coaxial pigtail catheter to keep it in place. The catheters were removed on the following day if radiographic examination showed no residual calculi. If residual stones were found, a second PNL was done. In some patients with gross haematuria or fever the nephrostomy catheter was kept in for another day. Patients were usually discharged the day after removal of the catheter. All ESWL treatments were carried out at Linkoping University Hospital using an unmodified Dornier HM-3 lithotripter. After 1 July, 1987 all patients (n= 15) were treated without anaesthesia; this was possible thanks to a voltage reduction to 14-16 kV and premedication with pethidine (75 mg) and diaze-
Table 111. Patients’ experience of the treatment PNL ( n = 17)
Duration of treatment Very tedious Rather tedious Indifferent Brief Pain during treatment Severe Moderate Little None Overall perception of treatment Frightening Unpleasant Rather unpleasant Not unpleasant
ESWL (n=25)
3
1
3 9 2
0 12 12
0 2 4 11
0 3 5 9
1
9 6 9
0 2 12 11
Data are missing for 4 and 3 patients respectively in each group. Scand J Urn1 Nephrol26
260
P. Carlsson et al.
Table IV. Post-treatment pain, use of analgesics, and fever while in hospital
Scand J Urol Nephrol Downloaded from informahealthcare.com by Nyu Medical Center on 02/20/15 For personal use only.
Day 1
Day 3
Day 5
PNL (n=18)
ESWL (n=25)
PNL (n=15)
ESWL (n=9)
PNL (n=10)
ESWL (n=4)
Pain Severe Moderate Little None
5 4 3 6
4
1 5
0
3 1 5
2
6
1 2 0 6
1
9 4 8
Analgesics Yes No
15 3
12 13
5 10
4
4 6
3
5
Fever ( > 38'C)' Yes No
1
16
0 25
9 15
2 7
0 10
0 4
a
3
1
1
1
One patient in the PNL group is missing.
pam (5 mg) given intramuscularly 30 min before treatment (8).
RESULTS Both mean treatment time and mean hospital stay were nearly twice as long for PNL as for ESWL. The range was greater in the PNL group (Table 11). Epidural anaesthesia was used for all PNL. One patient who required ureteroscopy and an-
other who required ureterolithotomy were given general anaesthesia. Roughly half the patients given ESWL were treated before the introduction of the anaesthetic-free procedure, and epidural (n=2) or spinal (n= 1) anaesthesia were used for them. Of 16 patients who responded satisfactorily to PNL, five were off work for a mean of 13.2 days between discharge and the first follow-up examination after four weeks. Only two of the
Table V. Pain, use of analgesics, and complications during the first nine days afer treatment Results expressed as percentage of group Day 3
Day 1
Day 5
PNL (n=18)
ESWL (n=24)
PNL (n= 18)
ESWL (n=23)
PNL ( n = 18)
ESWL (n=23)
YO
YO
YO
OO /
010
YO
Pain Nocturnal Persistent Used analgesics
7 28 6
29 38 29
22 22 6
13 30 22
11 11 11
13 17 17
Complications Hernaturia Fever (over 38°C)
28 6
26 8
6 6
14 4
16 11
17
Activities restricted
33
20
33
13
17
9
Scand J Urol Nephrol26
4
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Randomized comparison of ES W L and percutaneous nephrolithotomy 21 patients who responded well to ESWL took time off work (8 and 28 days, respectively). Patients' experience of the treatment is summarised in Table 111. There were only slight differences between the two groups. PNL generally took longer than ESWL, and consequently more patients in the PNL group found the operation tedious. On the other hand, slightly more patients undergoing ESWL had some degree of pain during treatment. and more in the PNL group found the treatment unpleasant. The PNL patients experienced further pain in hospital shortly after treatment, but the difference between the groups disappeared after five days (Table IV). Complications after treatment were more common after ESWL during the first 10 days after discharge, because of passage of fragments in the urine (Table V). More of the patients in the ESWL group experienced pain, but their pain did not restrict their normal daily activities any more than did the effects of PNL.
Clinical complications In the PNL group there was one case of septicaemia, one patient had a leaking nephrostomy catheter, one developed paralytic ileus because of leakage of fluid and there was one minor perforation of the renal pelvis. Among the ESWL patients one developed fever and one nausea and pain; three developed cutaneous haematomas probably as a result of the large number of shock waves used.
Day 9
Day 7 PNL (n=18)
PNL ( n = 18)
ESWL
(n=23)
YO
YO
YO
YO
ESWL
26 1
The results of treatment are summarised in Table VI.
Effectiveness of the treatment In the ESWL group six patients had residual stones of more than 5 mm in diameter after 12 months compared with one in the PNL group. Of these six, five had stones smaller than 8 mm. If patients with stone fragments of 5 mm or less (fragments that might easily pass spontaneously) are regarded as having had a successful outcome, the success rates after one year became 94% for PNL and 77% for ESWL. Symptoms In the PNL group there were 15 patients whose symptomatic responses were maintained at 12 months; 14 of these were completely free from symptoms (93 O/o) and one had had an infection with fever. In the ESWL group 19 of 2 1 patients were symptom free (91 O/O); one had some pain and one had pain, haematuria, and fever. Cost The mean total cost of El394 (range &68846420)/patient for ESWL was significantly lower than E2063 (range E763-$301 l)/patient for PNL (Table VII). The difference was even greater in a subgroup who had stones less than 2 cm in diameter. The cost/successfully treated patient after 12 months was E2196 for PNL and El810 for ESWL. The relatively low cost for ESWL is partly explained by the large turnover of patients at this particular centre. On the other hand, if ESWL is restricted to a small number of centres the travelling costs will be higher than if more lithotripters are used.
(n=23)
DISCUSSION 0 6 6
22 22
0 6 6
22 22
6 0
9 0
0 0
13 0
I1
13
11
9
17
13
Challah & Mays have discussed several factors that could make it difficult to mount a randomised trial (3), and the present study was only partly successful. The most important reasons for not taking part were fear of losing patients, budget restrictions, and lack of experience in PNL. The study is consequently relatively small, but the patients are comparable with regard to both stone classification and clinical history. We therefore think that the series was Scand J C'rol Nephrol 26
262
P. Carlsson et al.
Table VI. Number ofpatients free of stones afer four weeks and afer a year Four weeks
One year
PNL
PNL ESWL (n= 19) (n=26)
ESWL
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(n= 15) (n=25)
Free of stone Fragments < 5 mm Stones
11
8
15
11
4
11
3
9
> 5 mm
0 15
6 25
1
6 26
Total
19
big enough to allow valid conclusions to be drawn. The patient characteristics and results were, with a few exceptions, consistent with the previous findings in the Linkoping-Gothenburg study (2). The mean treatment time for category B stones changed from 123 min for PNL and 41 for ESWL in the Linkoping-Gothenburg study, to 79 and 43 min, respectively, in the present study (2), probably as a result of differences in technique-for example, endoscopic control was seldom used at the Karolinska Hospital. The mean hospital stay for ESWL did not change between the two studies, but the inpatient stay for PNL was shorter in the present study. The number of successfully treated patients was slightly higher in the Linkoping-Gothenburg study, 98 O/o of the PNL patients being free of stones after three months compared with 94% after six months in this study. The corresponding figures for ESWL were 87% (after four months) and 77% (after 12 months), respectively. We must emphasise that patients with residual fragments larger than 5 mm should be recommended to have a second session of ESWL, but for several reasons this was not done in the present study. It would have increased the cost, but would undoubtedly had resulted in a higher rate of stone-free patients. In the Linkoping-Gothenburg study the total cost/patient was rather lower for PNL, because the calculations were based on 1986 prices. The cost of ESWL dropped sharply between 1986 Scand J Urol Nephrol26
and 1988 because of the introduction of anaesthetic-free treatment in 1987, reduced expenditure for maintenance and electrodes, and an increase in the number of treatments given. The ESWL unit started operating in April 1985. During its second year in use (April 1986-March 1987) 846 treatments were carried out; during the period April 1988 - March 1989 this figure had risen to 1132. In the present study we assessed ESWL and PNL treatment of kidney stones from a number of aspects. In accordance with previous reports the results show that PNL results in a larger number of stone-free patients, an improvement that is, however, associated with higher costs both for the patient and for the health care system. In addition, the PNL patients had slightly more pain immediately after treatment, and had to stay in hospital longer. In contrast during the first 10 days at home, more ESWL patients had pain, possibly as a result of passage of stone fragments, but in the PNL group more patients perceived themselves restricted in daily activities and reported a significantly higher number of days off work. In the long term there was no difference in the length of time patients were free of symptoms. The disadvantage of referral to an ESWL centre a long way from home is of course difficult to evaluate in individual cases. There were only minor complications in both groups, though they were slightly more serious after PNL. The cost of treatment was significantly lower for ESWL, and as the Dornier HM-
Table VII. Total costs per patient (f) PNL
ESWL
P
AN patients
Number of
patients 21 Mean (SD) cost (E) 2 063 (1 31 5 ) Category B stones Number of patients 19 Mean (SD) cost (f) 2 061 ( 1 238)
28 1 394 (844)
>0.05
20 1 152 (231)
>0.003
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Randomized comparison of ES WL and percutaneous nephrolithotomy
3 was used, the current reduction in cost of electrodes indicates that the difference in costs will increase with time. The need for inpatient care after ESWL treatment is controversial. At some centres patients with small stones are treated as outpatients. In our study the mean hospital stay in a ward with less staff than the regular urology ward was 4.1 days including the day of treatment. One reason for the choice of inpatient treatment was to standardise the management of patients in the ESWL unit. This routine facilitates a high patient turnover, which reduces the costshession. We think that the possible reduction in total cost by treating some patients as outpatients is relatively small. We conclude that medium sized kidney stones (6-30 mm, or 2-3 stones less or equal to 20 mm) can be efficiently and cheaply treated by both PNL and ESWL, significantly lower. Even if effects other than cost (such as complications and patients’ experience) are borne in mind, ESWL is superior to PNL for this group of patients. REFERENCES 1. Aronne LJ, Braham RL, Richte R, Vaughan DE,
Ruchlin HS. Cost-effectiveness of extracorporeal shock-wave lithotripsy. Endourology 1988; 3 1 : 225-230.
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2. Carlsson P, NauclCr J, Petterson S, Tiselius H-G. A cost-effectiveness analysis of extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy. Scand J Urol Nephrol 1989; Suppl. 122. 3. Challah S, Mays NB. The randomised controlled trial in the evaluation of new technology: a case study. Br Med J 1986; 292: 877-878. 4. Chang CR, Webb DR, Payne SR, Wickham JEA. Comparison of treatment of renal calculi by open surgery, percutaneous nephrolithotomy, and extracorporeal shockwave lithotripsy. Br Med J 1986; 292: 879-882. 5. Kirchberger S. The diffusion of two technologies for renal stone treatment across Europe. London: King’s Fund Centre for Health Services Development, 1991. 6. Lingeman JE, Saywell RM, Woods JR, Newman DM. Cost analysis of extracorporeal shock wave lithotripsy relative to other surgical and non-surgical treatment alternatives for urolithiasis. Med Care 1986; 24: 1151-1160. 7. Mays N, Challah S, Patel S, Palfrey E, Creeser R, Vadera P, Burey P. Clinical comparison of extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy in treating renal calculi. Br Med J 1988; 297: 253-258. 8. Petterson B. Extracorporeal shock wave lithotripsy of renal and ureteral stones-studies on indications, methods and results. Linkoping University Medical Dissertations No 293, 1989. 9. Tiselius H-G, Petterson B, Hellgren E, Carlsson P. Classification of patients subjected to extracorporeal shock wave lithotripsy. Scand J Urol Nephrol 1988; 22: 65-70.
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