Abstract
Background
There are three reconstructive options after colectomy for ulcerative colitis (UC), ileal pouch anal anastomosis, ileorectal anastomosis and continent ileostomy. Less than 50% of UC patients in Sweden get bowel continuity after colectomy. The aim was to investigate the correlation between reconstructive volumes of the hospital performing the colectomy and the likelihood of reconstruction.
Methods
From the Swedish National Patient Register, all ulcerative colitis patients subjected to colectomy between 1997 and 2020 were identified, and patient demographics, surgeries and hospital reconstructive volumes were extracted. Cox regression models of time from colectomy to reconstruction were performed, including age, sex, calendar time of colectomy, time from diagnosis, primary sclerosing cholangitis and pelvic pouch volume in the models. The patients were divided into groups depending on the annual number of pelvic pouches performed at the hospital performing the colectomy: 0, 1–3, 4–7, >7.
Results
Colectomy was performed in 4112 patients, 1932 (47%) patients were reconstructed. Restorative surgery was more common in high‐volume versus low‐volume units (62% vs. 38%). Ileorectal anastomosis was slightly more common than pelvic pouch (964 (50%) vs. 927 (48%)), but in high‐volume units only 30% of the reconstructed patients received an ileorectal anastomosis. The chance of pelvic pouch increased with each volume category (HR: 1; 1.49; 1.79; 2.22 (p < 0.001)).
Conclusion
The likelihood of receiving pouch surgery depends on the hospital where the colectomy was performed, which must be considered in the future organization of UC‐surgery.
Keywords: colectomy, pelvic pouch, reconstructive surgery, ulcerative colitis
What does this paper add to the literature?
Many colectomies are performed at hospitals with limited reconstructive experience. This first national population‐based study on the chance of reconstruction based on pelvic pouch volume shows an increased chance for reconstruction if colectomy is performed at hospitals with higher pelvic pouch volume. This knowledge is relevant for reorganization of IBD care.
INTRODUCTION
Ulcerative colitis (UC) is an inflammatory bowel disease isolated to the colon and rectum. The prevalence of UC is highest in northwestern Europe and north America with an estimated prevalence between 156 and 505 cases per 100 000 [1, 2]. The mainstay of treatment for UC is pharmacological [3] yet between 6 and 19% of UC patients undergo colectomy within 10 years of disease onset. There is currently a lack of long‐term follow up data since the introduction of biological treatment [4, 5, 6, 7, 8]. The causes for colectomy in UC patients are either acute flair not responding to intravenous steroids or advanced medical therapy, chronic therapy refractory or steroid dependent UC and dysplasia or cancer [9, 10, 11].
There are generally four options available to the UC patient after colectomy; however, all options will not be suitable to all UC patients subjected to colectomy [10]. One option available to all patients subjected to colectomy is to maintain the end ileostomy, often with completion proctectomy later. The gold standard method for reconstruction after colectomy for UC is the ileal pouch anal anastomosis (IPAA) [12, 13]. The other option where the faecal continuity is restored is the ileorectal anastomosis (IRA) [14, 15, 16, 17]. For patients not suitable for neither IPAA nor IRA but still wishing to avoid a stoma appliance, the remaining option is the continent ileostomy or Kock pouch [18, 19, 20].
The impact of hospital surgical volume on surgical outcomes has been the subject of scrutiny for the past two decades [21, 22]. Increased hospital volume has been associated with reduced mortality and morbidity after colectomy [23, 24, 25], and a lower rate of IPAA failure with a cut‐off for high‐volume centres at an average of 8.4 IPAA procedures per annum [26].
Despite the available restorative options after colectomy, less than half of the UC patients subjected to colectomy in Sweden and no more than one third of the patients in England or the United States ever get reconstructed [23, 27]. A higher proportion, 67%, was recently reported in a populations‐based study from France [28]. There is one study indicating a higher proportion of IPAA compared to only subtotal colectomy among UC patients subjected to colectomy at Academic hospitals and hospitals performing more IPAA procedures [29]. There are, to our knowledge, no studies on the proportions of both IPAA and IRA based on the volumes of reconstructions at the centre performing the colectomy.
In this study, we aimed to investigate the correlation between reconstructive volumes (defined as annual number of IPAA procedures) of the hospital performing the colectomy and the likelihood of reconstruction with IRA or IPAA.
MATERIALS AND METHODS
This is a nationwide register‐linked cohort study including Swedish patients with UC. Register linkages are made possible through a unique personal identity number, which is assigned to all permanent Swedish residents [30]. This allows for nationwide follow‐up in health care registers as well as crossmatching between different registers. The Swedish National Patient Register (NPR) holds information on discharge diagnoses, performed surgical interventions, dates for admission and discharge and admitting hospital. The register started in 1964 and is considered to have full national coverage since 1987. Originally, only inpatient admissions were recorded but since 2001 specialist outpatient care visits are also registered [31, 32].
All patients with two entries or more of UC in NPR and the first diagnosis entry between 1987 and June 2020 were identified. Patients who had been subjected to colectomy between the ages of 20 and 70 years and between the years 1997 and June 2020 were identified by means of NOMESCO procedure codes (Table S1) ICD and ATC codes used to define comorbidity and drug use are presented in Table S2. The ‘wash out’ period between 1987 and 1997 was utilized to avoid including patients that were already subjected to colectomy.
Exposure
The exposure of interest was annual IPAA procedures in IBD patients rather than total annual reconstructions. IPAA is the more challenging procedure and all Swedish centres performing IPAA perform IRA but not the other way around [14]. Hospital volume of IPAA surgery was based on the yearly average number of IPAA procedures performed at the centre that had performed the colectomy divided into four groups: 0; 0<−≤3; 3<−≤7; >7. The yearly number of IPAAs performed differed substantially within some hospitals over the study period. We used the average annual number of IPAA procedures in the 3 years preceding the year of colectomy to categorize hospital volume. Hence, the same hospital could be in different volume categories in different time periods as their IPAA volumes varied over the study period. In the beginning of the study period, the IPAA procedures were scattered over more smaller hospitals but at the end of the study period some small hospitals performed a very limited number of IPAA procedures.
Outcome
The primary outcome of interest was the rate of restorative surgery. In the main analysis, only the first restorative procedure was accounted for. Patients were followed from colectomy discharge until admission for restorative procedures, migration, death or 30th of June 2020, whichever occurred first. In the analyses of IPAA surgery, patients that received an IRA were censored at the date of admission for IRA surgery. Similarly, in the analyses of IRA surgery, patients that received an IPAA were censored at the time of surgery.
Statistics
The rate of restorative surgery with IPAA or IRA was calculated using the Kaplan Meier method and Cox regression analyses. The main exposure was hospital volume of IPAA surgery. The multivariable hazard ratios (HR) derived from the Cox proportional hazard model were adjusted for sex, age at colectomy (20–29 years/30–39 years/40–49 years/50–59 years/60–69 years), duration of UC (<30 days/30–365 days/>365 days), calendar period (1997–2003/2004–2010/2011–2020), educational level (≤9, 10–12, >12) and presence of primary sclerosing cholangitis (PSC). Further adjustment was made for the presence of colorectal cancer, and in a mediation analysis, adjustment was made for open or laparoscopic colectomy. There was no violation of the proportional hazard assumption. The statistical analysis was performed using SAS 9.4 software. Statistical significance was accepted at p < 0.05.
Ethics
Ethical approval was obtained from the ethical review board of the Stockholm region (2007/785‐31/5; 2011/1509‐32; 2012/601‐32, 2015/0004–31, 2015/615‐32, 2015/1030‐ 32, 2015/2237‐32, 2016/1929‐32, 2017/1959‐32).
RESULTS
We identified 66 143 patients with an incident diagnosis of UC between 1987 and 2020, out of which 5194 were subjected to colectomy between 1997 and 2020. Of these patients, 327 (6.3%) had their colectomy before the age of 20 years, 615 (11.8%) after the age of 70 years, and 140 (2.7%) were reported to already have been subjected to colectomy before the onset of UC. This rendered a cohort of 4112 adult UC patients subjected to colectomy between January 1997 and June 2020. Of these patients, 1932 (47.0%) were reconstructed by 30th June 2022. Figure 1.
FIGURE 1.
Flow chart over the UC colectomy cohort.
In the colectomy cohort, there were 1528 (37.2%) women, the median (IQR) age of UC onset was 36.1 (25.4–50.1) years, and the median (IQR) age at colectomy was 41.9 (30.3–55.1) years. The median (IQR) time from UC onset to colectomy was 2.7 (0.5–7.8) years, and 684 (16.6%) had their colectomy within 30 days of UC onset. The presence of PSC was reported in 263 (6.4%) of the patients and colorectal cancer among 382 (9.3%). Demographic characteristics of the colectomy and reconstruction cohorts are presented in Tables 1 and 2, respectively.
TABLE 1.
Characteristics of the study cohort at the time of colectomy.
| Variable | Overall | Mean number of IPAA surgeries by hospital and calendar year | |||
|---|---|---|---|---|---|
| 0 | 0<−≤ 3 | 3<−≤ 7 | >7 | ||
| N | 4112 | 1137 | 1421 | 1098 | 456 |
| Sex, n (%) | |||||
| Female | 1528 (37.2%) | 395 (34.7%) | 521 (36.7%) | 438 (39.9%) | 174 (38.2%) |
| Male | 2584 (62.8%) | 742 (65.3%) | 900 (63.3%) | 660 (60.1%) | 282 (61.8%) |
| Age at UC diagnosis | |||||
| Median (IQR) | 36.1 (25.4–50.1) | 38.8 (26.6–53.1) | 36.6 (25.3–50.7) | 34.2 (24.2–48.3) | 34.2 (25.6–47.6) |
| Categories, n (%) | |||||
| <18 years | 253 (6.2%) | 55 (4.8%) | 86 (6.1%) | 91 (8.3%) | 21 (4.6%) |
| 18–29 years | 1270 (30.9%) | 304 (26.7%) | 434 (30.5%) | 360 (32.8%) | 172 (37.7%) |
| 30–39 years | 830 (20.2%) | 233 (20.5%) | 286 (20.1%) | 226 (20.6%) | 85 (18.6%) |
| 40–49 years | 721 (17.5%) | 214 (18.8%) | 241 (17.0%) | 181 (16.5%) | 85 (18.6%) |
| 50–69 years | 1038 (25.2%) | 331 (29.1%) | 374 (26.3%) | 240 (21.9%) | 93 (20.4%) |
| ≥70 years | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| Age at colectomy | |||||
| Median (IQR) | 41.9 (30.3–55.1) | 44.3 (31.8–57.7) | 41.7 (29.7–55.6) | 39.8 (30.3–53.0) | 39.2 (29.4–52.5) |
| Categories, n (%) | |||||
| <20 years | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| 20–29 years | 998 (24.3%) | 236 (20.8%) | 370 (26.0%) | 269 (24.5%) | 123 (27.0%) |
| 30–39 years | 904 (22.0%) | 228 (20.1%) | 280 (19.7%) | 284 (25.9%) | 112 (24.6%) |
| 40–49 years | 780 (19.0%) | 226 (19.9%) | 261 (18.4%) | 208 (18.9%) | 85 (18.6%) |
| 50–69 years | 1430 (34.8%) | 447 (39.3%) | 510 (35.9%) | 337 (30.7%) | 136 (29.8%) |
| ≥70 years | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| Year of colectomy, n (%) | |||||
| 1997–2003 | 1437 (34.9%) | 449 (39.5%) | 403 (28.4%) | 353 (32.1%) | 232 (50.9%) |
| 2004–2010 | 1273 (31.0%) | 296 (26.0%) | 524 (36.9%) | 320 (29.1%) | 133 (29.2%) |
| 2011–2020 | 1402 (34.1%) | 392 (34.5%) | 494 (34.8%) | 425 (38.7%) | 91 (20.0%) |
| Time from UC onset to colectomy (years) | |||||
| Median (IQR) | 2.7 (0.5–7.8) | 2.2 (0.3–7.1) | 2.8 (0.4–7.6) | 3.4 (0.7–9.1) | 2.4 (0.3–7.3) |
| Categories, n (%) | |||||
| <30 days | 684 (16.6%) | 206 (18.1%) | 239 (16.8%) | 150 (13.7%) | 89 (19.5%) |
| 30–365 days | 637 (15.5%) | 188 (16.5%) | 222 (15.6%) | 168 (15.3%) | 59 (12.9%) |
| >1 year | 2791 (67.9%) | 743 (65.3%) | 960 (67.6%) | 780 (71.0%) | 308 (67.5%) |
| Comorbidities, n (%) | |||||
| Extraintestinal manifestations (excl. PSC) | 532 (12.9%) | 125 (11.0%) | 185 (13.0%) | 164 (14.9%) | 58 (12.7%) |
| PSC | 263 (6.4%) | 58 (5.1%) | 86 (6.1%) | 79 (7.2%) | 40 (8.8%) |
| Colorectal cancer | 382 (9.3%) | 110 (9.7%) | 126 (8.9%) | 114 (10.4%) | 32 (7.0%) |
| Mean annual number of restorative surgeries by hospital | |||||
| Mean (SD) | 6.6 (6.7) | 1.1 (1.2) | 4.4 (3.8) | 10.7 (5.9) | 16.9 (6.0) |
| Median (IQR) | 5 (2–9) | 1 (0–2) | 3 (2–6) | 8 (6–14) | 15 (12–21) |
| Mean annual number of IPAA surgeries by hospital | |||||
| Mean (SD) | 2.9 (3.3) | 0.0 (0.0) | 1.5 (0.9) | 4.8 (1.2) | 9.7 (2.8) |
| Median (IQR) | 2 (0–5) | 0 (0–0) | 1 (1–2) | 5 (4–6) | 9 (8–11) |
| Range, min–max | 0–21 | 0–0 | 0–3 | 3–7 | 7–21 |
| Mean annual number of IRA surgeries by hospital | |||||
| Mean (SD) | 3.3 (4.0) | 1.1 (1.2) | 2.8 (3.1) | 5.3 (5.0) | 5.9 (4.3) |
| Median (IQR) | 2 (1–4) | 1 (0–2) | 2 (1–4) | 4 (1–7) | 5 (3–7) |
| Follow‐up time from colectomy to any restorative surgery (years) | |||||
| Mean (SD) | 6.3 (7.3) | 7.3 (7.7) | 6.2 (7.1) | 5.5 (6.9) | 6.1 (7.7) |
| Median (IQR) | 2.3 (0.6–11.4) | 3.5 (1.0–13.7) | 2.6 (0.6–11.3) | 1.6 (0.4–9.0) | 1.3 (0.0–14.4) |
TABLE 2.
Characteristics of the study cohort at the time of restorative surgery.
| Variable | Overall | Mean number of IPAA surgeries by hospital and calendar year | |||
|---|---|---|---|---|---|
| 0 | 0<−≤3 | 3<−≤7 | >7 | ||
| N | 1932 | 287 | 674 | 644 | 327 |
| Sex, n (%) | |||||
| Female | 691 (35.8%) | 106 (36.9%) | 239 (35.5%) | 221 (34.3%) | 125 (38.2%) |
| Male | 1241 (64.2%) | 181 (63.1%) | 435 (64.5%) | 423 (65.7%) | 202 (61.8%) |
| Age at UC diagnosis | |||||
| Mean (SD) | 34.4 (13.4) | 36.6 (14.5) | 34.1 (13.4) | 33.7 (13.0) | 34.8 (12.7) |
| Median (IQR) | 32.5 (23.6–44.4) | 34.9 (23.9–48.1) | 32.8 (22.9–43.6) | 31.5 (23.1–43.5) | 32.8 (25.1–44.1) |
| Range, min–max | 4.8–69.8 | 9.7–67.0 | 8.1–69.8 | 4.8–68.8 | 7.1–65.6 |
| Categories, n (%) | |||||
| <18 years | 142 (7.3%) | 18 (6.3%) | 53 (7.9%) | 54 (8.4%) | 17 (5.2%) |
| 18–29 years | 722 (37.4%) | 95 (33.1%) | 247 (36.6%) | 254 (39.4%) | 126 (38.5%) |
| 30–39 years | 425 (22.0%) | 61 (21.3%) | 164 (24.3%) | 134 (20.8%) | 66 (20.2%) |
| 40–49 years | 349 (18.1%) | 51 (17.8%) | 116 (17.2%) | 108 (16.8%) | 74 (22.6%) |
| 50–69 years | 294 (15.2%) | 62 (21.6%) | 94 (13.9%) | 94 (14.6%) | 44 (13.5%) |
| ≥70 years | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| Age at restorative surgery | |||||
| Mean (SD) | 40.5 (12.8) | 43.0 (13.8) | 39.9 (12.9) | 40.1 (12.3) | 40.4 (12.2) |
| Median (IQR) | 38.8 (29.6–50.2) | 42.4 (30.8–54.4) | 38.3 (29.0–49.3) | 38.4 (29.7–49.6) | 38.9 (30.4–49.6) |
| Range, min–max | 20.1–70.5 | 20.2–69.5 | 20.5–70.5 | 20.3–69.5 | 20.1–70.4 |
| Categories, n (%) | |||||
| <20 years | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| 20–29 years | 502 (26.0%) | 62 (21.6%) | 196 (29.1%) | 168 (26.1%) | 76 (23.2%) |
| 30–39 years | 513 (26.6%) | 68 (23.7%) | 171 (25.4%) | 180 (28.0%) | 94 (28.7%) |
| 40–49 years | 424 (21.9%) | 63 (22.0%) | 145 (21.5%) | 138 (21.4%) | 78 (23.9%) |
| 50–69 years | 491 (25.4%) | 94 (32.8%) | 161 (23.9%) | 158 (24.5%) | 78 (23.9%) |
| ≥70 years | 2 (0.1%) | 0 (0.0%) | 1 (0.1%) | 0 (0.0%) | 1 (0.3%) |
| Year of colectomy, n (%) | |||||
| 1997–2003 | 666 (34.5%) | 94 (32.8%) | 176 (26.1%) | 219 (34.0%) | 177 (54.1%) |
| 2004–2010 | 686 (35.5%) | 85 (29.6%) | 297 (44.1%) | 218 (33.9%) | 86 (26.3%) |
| 2011–2020 | 580 (30.0%) | 108 (37.6%) | 201 (29.8%) | 207 (32.1%) | 64 (19.6%) |
| Time from UC onset to colectomy (years) | |||||
| Median (IQR) | 3.1 (0.7–7.8) | 4.0 (1.0–8.7) | 3.3 (0.7–7.5) | 3.3 (0.7–8.1) | 2.0 (0.4–7.1) |
| Categories, n (%) | |||||
| <30 days | 284 (14.7%) | 33 (11.5%) | 95 (14.1%) | 103 (16.0%) | 53 (16.2%) |
| 30–365 days | 281 (14.5%) | 38 (13.2%) | 100 (14.8%) | 87 (13.5%) | 56 (17.1%) |
| >1 year | 1367 (70.8%) | 216 (75.3%) | 479 (71.1%) | 454 (70.5%) | 218 (66.7%) |
| Year of restorative surgery, n (%) | |||||
| 1997–2003 | 569 (29.5%) | 86 (30.0%) | 143 (21.2%) | 188 (29.2%) | 152 (46.5%) |
| 2004–2010 | 686 (35.5%) | 80 (27.9%) | 300 (44.5%) | 210 (32.6%) | 96 (29.4%) |
| 2011–2020 | 677 (35.0%) | 121 (42.2%) | 231 (34.3%) | 246 (38.2%) | 79 (24.2%) |
| Time from colectomy to restorative surgery (years) | |||||
| Median (IQR) | 0.6 (0.0–1.2) | 0.0 (0.0–1.1) | 0.6 (0.0–1.2) | 0.7 (0.0–1.3) | 0.7 (0.0–1.5) |
| Categories, n (%) | |||||
| Primary (0 days) | 757 (39.2%) | 153 (53.3%) | 263 (39.0%) | 223 (34.6%) | 118 (36.1%) |
| Not primary (>0 days) | 1175 (60.8%) | 134 (46.7%) | 411 (61.0%) | 421 (65.4%) | 209 (63.9%) |
| Comorbidities, n (%) | |||||
| Extraintestinal manifestations (excl. PSC) | 287 (14.9%) | 37 (12.9%) | 104 (15.4%) | 101 (15.7%) | 45 (13.8%) |
| PSC | 141 (7.3%) | 17 (5.9%) | 50 (7.4%) | 48 (7.5%) | 26 (8.0%) |
| Colorectal cancer | 203 (10.5%) | 37 (12.9%) | 72 (10.7%) | 70 (10.9%) | 24 (7.3%) |
| Mean annual number of restorative surgeries by hospital | |||||
| Mean (SD) | 8.6 (7.1) | 1.3 (1.3) | 5.2 (3.9) | 10.8 (6.0) | 17.4 (6.0) |
| Median (IQR) | 6 (3–13) | 1 (0–2) | 4 (3–6) | 8 (6–14) | 15 (13–23) |
| Range, min–max | 0–30 | 0–7 | 0–24 | 3–29 | 8–30 |
| Mean annual number of IPAA surgeries by hospital | |||||
| Mean (SD) | 3.9 (3.6) | 0.0 (0.0) | 1.6 (0.9) | 4.9 (1.2) | 10.0 (2.9) |
| Median (IQR) | 3 (1–6) | 0 (0–0) | 2 (1–2) | 5 (4–6) | 9 (8–12) |
| Range, min–max | 0–21 | 0–0 | 0–3 | 3–7 | 7–21 |
| Mean annual number of IRA surgeries by hospital | |||||
| Mean (SD) | 4.2 (4.3) | 1.3 (1.3) | 3.4 (3.3) | 5.4 (5.1) | 6.0 (4.4) |
| Median (IQR) | 3 (1–6) | 1 (0–2) | 3 (1–4) | 4 (1–8) | 5 (3–8) |
| Range, min–max | 0–20 | 0–7 | 0–20 | 0–20 | 1–19 |
| Type of surgery, n (%) | |||||
| IRA | 964 (49.9%) | 240 (83.6%) | 354 (52.5%) | 271 (42.1%) | 99 (30.3%) |
| Primary | 431 (22.3%) | 133 (46.3%) | 152 (22.6%) | 104 (16.1%) | 42 (12.8%) |
| IPAA | 927 (48.0%) | 45 (15.7%) | 310 (46.0%) | 359 (55.7%) | 213 (65.1%) |
| Primary | 320 (16.6%) | 20 (7.0%) | 109 (16.2%) | 116 (18.0%) | 75 (22.9%) |
| Continent ileostomy | 41 (2.1%) | 2 (0.7%) | 10 (1.5%) | 14 (2.2%) | 15 (4.6%) |
| Primary | 6 (0.3%) | 0 (0.0%) | 2 (0.3%) | 3 (0.5%) | 1 (0.3%) |
| Follow‐up time from restorative surgery to any failure (years) | |||||
| Mean (SD) | 11.4 (7.0) | 11.0 (7.3) | 11.2 (6.7) | 11.2 (7.0) | 12.8 (7.4) |
| Median (IQR) | 11.4 (5.3–17.1) | 10.3 (4.9–16.4) | 11.5 (5.4–16.3) | 10.8 (5.3–16.5) | 15.3 (5.4–19.3) |
| Range, min–max | 0.0–25.5 | 0.0–25.3 | 0.0–25.5 | 0.0–25.4 | 0.0–24.8 |
| Categories, n (%) | |||||
| <1 year | 116 (6.0%) | 16 (5.6%) | 36 (5.3%) | 46 (7.1%) | 18 (5.5%) |
| 1–<5 years | 340 (17.6%) | 56 (19.5%) | 122 (18.1%) | 104 (16.1%) | 58 (17.7%) |
| 5–<10 years | 388 (20.1%) | 67 (23.3%) | 134 (19.9%) | 138 (21.4%) | 49 (15.0%) |
| ≥10 years | 1088 (56.3%) | 148 (51.6%) | 382 (56.7%) | 356 (55.3%) | 202 (61.8%) |
| Reason for censoring, n (%) | |||||
| Failure | 333 (17.2%) | 52 (18.1%) | 123 (18.2%) | 104 (16.1%) | 54 (16.5%) |
| Death | 147 (7.6%) | 27 (9.4%) | 40 (5.9%) | 46 (7.1%) | 34 (10.4%) |
| Emigration | 44 (2.3%) | 3 (1.0%) | 18 (2.7%) | 16 (2.5%) | 7 (2.1%) |
| End of data (June 30, 2022) | 1408 (72.9%) | 205 (71.4%) | 493 (73.1%) | 478 (74.2%) | 232 (70.9%) |
The cohort was subjected to a total of 1932 (47.0%) reconstructions, 964 (49.9%) IRA, 927 (48.0%) IPAA and 41 (2.1%) CI procedures. The CIs, constituting only 2.1% of all reconstructions, were not included in further analysis.
The number of IPAAs performed at the colectomy hospital was significantly associated with the probability of getting an IPAA and increased with every volume category (HR: 1; 1.50 95% CI (1.25–1.79); 1.80 95% CI (1.50–2.16); 2.13 95% CI (1.71–2.64)) Figure 2 describes the cumulative chance of pouch surgery stratified by hospital volume. There was no significant difference in the chance of receiving an IRA depending on the IPAA volumes at the colectomy hospital during the previous 3 years, Figure 3. The multivariable regression models of hospital volume and the chances of getting IPAA or IRA after colectomy are summarized in Tables 3 and 4 respectively. Univariable and multivariable regression models for the chance of IRA or IPAA surgery after colectomy are presented in Table S3.
FIGURE 2.
Time to IPAA surgery after colectomy in groups of mean annual number of IPAA surgeries by hospital.
FIGURE 3.
Time to IRA surgery after colectomy in groups of mean annual number of IPAA surgeries by hospital.
TABLE 3.
Univariable and multivariable Cox proportional hazard regression models for the chance of IPAA surgery after colectomy (n = 4112).
| Variable | N | N IPAA (%) | Univariate model | Multivariate model | ||
|---|---|---|---|---|---|---|
| HR (95%CI) | p‐value | HR (95%CI) | p‐value | |||
| Sex | ||||||
| Female (reference) | 1528 | 331 (21.7%) | 1.00 | – | 1.00 | – |
| Male | 2584 | 596 (23.1%) | 1.09 (0.96–1.25) | 0.19 | 1.14 (1.00–1.31) | 0.055 |
| Age | ||||||
| 20–29 years | 998 | 268 (26.9%) | 5.27 (3.78–7.35) | <0.001 | 4.78 (3.40–6.73) | <0.001 |
| 30–39 years | 904 | 278 (30.8%) | 6.17 (4.42–8.60) | <0.001 | 5.64 (4.01–7.92) | <0.001 |
| 40–49 years | 780 | 214 (27.4%) | 5.29 (3.77–7.42) | <0.001 | 4.91 (3.49–6.92) | <0.001 |
| 50–59 years | 766 | 127 (16.6%) | 2.95 (2.07–4.22) | <0.001 | 2.75 (1.92–3.93) | <0.001 |
| 60–69 years (reference) | 664 | 40 (6.0%) | 1.00 | – | 1.00 | – |
| Year | ||||||
| 1997–2003 (reference) | 1437 | 430 (29.9%) | 1.00 | – | 1.00 | – |
| 2004–2010 | 1273 | 288 (22.6%) | 0.81 (0.70–0.94) | 0.005 | 0.81 (0.69–0.94) | 0.006 |
| 2011–2020 | 1402 | 209 (14.9%) | 0.56 (0.47–0.66) | <0.001 | 0.57 (0.48–0.68) | <0.001 |
| PSC | ||||||
| No (reference) | 3849 | 877 (22.8%) | 1.00 | – | 1.00 | – |
| Yes | 263 | 50 (19.0%) | 1.01 (0.75–1.35) | 0.96 | 0.92 (0.68–1.24) | 0.59 |
| Time from UC diagnosis to colectomy | ||||||
| <30 days (reference) | 684 | 150 (21.9%) | 1.00 | – | 1.00 | – |
| 30–365 days | 637 | 149 (23.4%) | 1.15 (0.92–1.43) | 0.22 | 1.24 (0.99–1.55) | 0.057 |
| >365 days | 2791 | 628 (22.5%) | 1.19 (1.00–1.42) | 0.045 | 1.34 (1.12–1.61) | 0.002 |
| Mean annual number of IPAA surgeries by hospital | ||||||
| 0 (reference) | 1137 | 180 (15.8%) | 1.00 | – | 1.00 | – |
| 0<−≤3 | 1421 | 311 (21.9%) | 1.48 (1.24–1.78) | <0.001 | 1.50 (1.25–1.79) | <0.001 |
| 3<−≤7 | 1098 | 286 (26.0%) | 1.87 (1.56–2.25) | <0.001 | 1.80 (1.50–2.16) | <0.001 |
| >7 | 456 | 150 (32.9%) | 2.46 (1.99–3.04) | <0.001 | 2.13 (1.71–2.64) | <0.001 |
| Level of education, n (%) | ||||||
| <9 years(reference) | 766 | 150 (19.6%) | 1.00 | – | 1.00 | – |
| 10–12 years | 2088 | 496 (23.8%) | 1.31 (1.10–1.57) | 0.003 | 1.00 (0.83–1.21) | 1.00 |
| ≥13 years | 1170 | 272 (23.2%) | 1.36 (1.12–1.66) | 0.002 | 0.95 (0.78–1.17) | 0.64 |
| Missing | 88 | 9 (10.2%) | 0.99 (0.51–1.92) | 0.99 | 0.84 (0.44–1.60) | 0.59 |
TABLE 4.
Univariable and multivariable Cox proportional hazard regression models for the chance of IRA surgery after colectomy (n = 4112).
| Variable | N | N IRA (%) | Univariable model | Multivariable model | ||
|---|---|---|---|---|---|---|
| HR (95%CI) | p‐value | HR (95%CI) | p‐value | |||
| Sex | ||||||
| Female (reference) | 1528 | 342 (22.4%) | 1.00 | – | 1.00 | – |
| Male | 2584 | 622 (24.1%) | 1.09 (0.96–1.24) | 0.19 | 1.11 (0.97–1.26) | 0.13 |
| Age | ||||||
| 20–29 years | 998 | 284 (28.5%) | 1.91 (1.54–2.38) | <0.001 | 1.80 (1.44–2.25) | <0.001 |
| 30–39 years | 904 | 216 (23.9%) | 1.65 (1.31–2.07) | <0.001 | 1.50 (1.19–1.90) | <0.001 |
| 40–49 years | 780 | 185 (23.7%) | 1.58 (1.25–2.00) | <0.001 | 1.54 (1.21–1.95) | <0.001 |
| 50–59 years | 766 | 168 (21.9%) | 1.39 (1.09–1.76) | 0.007 | 1.37 (1.08–1.74) | 0.010 |
| 60–69 years (reference) | 664 | 111 (16.7%) | 1.00 | – | 1.00 | – |
| Year | ||||||
| 1997–2003 (reference) | 1437 | 218 (15.2%) | 1.00 | – | 1.00 | – |
| 2004–2010 | 1273 | 386 (30.3%) | 2.09 (1.77–2.46) | <0.001 | 2.02 (1.70–2.39) | <0.001 |
| 2011–2020 | 1402 | 360 (25.7%) | 1.78 (1.51–2.11) | <0.001 | 1.70 (1.42–2.02) | <0.001 |
| PSC | ||||||
| No (reference) | 3849 | 881 (22.9%) | 1.00 | – | 1.00 | – |
| Yes | 263 | 83 (31.6%) | 1.60 (1.29–1.99) | <0.001 | 1.25 (1.00–1.56) | 0.054 |
| Time from UC diagnosis to colectomy | ||||||
| <30 days (reference) | 684 | 129 (18.9%) | 1.00 | – | 1.00 | – |
| 30–365 days | 637 | 127 (19.9%) | 1.12 (0.89–1.43) | 0.33 | 1.04 (0.82–1.31) | 0.77 |
| >365 days | 2791 | 708 (25.4%) | 1.52 (1.26–1.82) | <0.001 | 1.23 (1.02–1.48) | 0.032 |
| Mean annual number of IPAA surgeries by hospital | ||||||
| 0 (reference) | 1137 | 257 (22.6%) | 1.00 | – | 1.00 | – |
| 0<−≤3 | 1421 | 326 (22.9%) | 1.08 (0.92–1.27) | 0.34 | 0.97 (0.83–1.14) | 0.72 |
| 3<−≤7 | 1098 | 279 (25.4%) | 1.25 (1.06–1.48) | 0.008 | 1.12 (0.95–1.32) | 0.18 |
| >7 | 456 | 102 (22.4%) | 1.14 (0.91–1.43) | 0.24 | 1.11 (0.89–1.39) | 0.36 |
| Level of education, n (%) | ||||||
| <9 years (reference) | 766 | 135 (17.6%) | 1.00 | – | 1.00 | – |
| 10–12 years | 2088 | 491 (23.5%) | 1.41 (1.17–1.70) | <0.001 | 1.23 (1.02–1.49) | 0.033 |
| ≥13 years | 1170 | 330 (28.2%) | 1.78 (1.46–2.16) | <0.001 | 1.50 (1.23–1.83) | <0.001 |
| Missing | 88 | 8 (9.1%) | 0.86 (0.42–1.74) | 0.67 | 0.66 (0.33–1.34) | 0.25 |
In addition to hospital volume, sex, calendar period, PSC, timing of colectomy and age were also associated with the chance of pouch surgery. The rate of getting an IPAA was slightly higher among male than female UC patients (HR 1.14, 95% CI 1.00–1.31). There was a tendency towards a higher chance for men to get an IRA as well; however, this was not significant (HR 1.11, 95% CI 0.97–1.26). The probability of receiving an IPAA decreased during the study period, while the chance of receiving an IRA increased from 1997 and onwards. PSC was associated with an increased probability of getting an IRA (HR 1.25 (95% CI 1.00–1.56)) but was not associated with any difference in the probability of getting an IPAA. Being subjected to colectomy within 30 days of the first UC diagnosis was associated with a significantly decreased chance of getting either an IRA or an IPAA versus >365 days. A higher level of education was associated with an increased chance for IRA (>12 years of education HR 1.50 95% CI 1.23–1.83) but the level of education did not affect the chance for IPAA. The chance of getting an IPAA was highest in the age period between 30 and 39 years of age, with an HR of 5.59 (95% CI 4.00–7.82) compared to reference (1.0) between 60 and 69 years of age. The chance of getting an IRA was highest between the age of 20 and 29 years of age (HR 1.93 95% CI 1.55–2.41). The presence of colorectal cancer did not affect the chance for reconstruction, and additional adjustments for colorectal cancer yielded identical results for the primary exposure (hospital volume). Open surgery, as compared to laparoscopic surgery, was associated with a significant reduction in the chance of receiving any reconstruction (HR 0.32 95% CI 0.29–0.35), but adding the variable in the multivariable cox regression model did not impact the associations between hospital volume and the chance of pouch surgery.
During follow‐up, 169 patients with IRA failed. Of those, 67 patients (35%) were converted to an IPAA.
DISCUSSION
In this national cohort of 66 143 patients, including 4112 patients treated with colectomy, hospital volume of IPAA surgery was associated with an increased chance of receiving an IPAA. The finding of an increasing chance for IPAA with increasing IPAA volume at the colectomy is in line with similar previous publications [28, 29].
It is not likely that these findings represent a difference in patient characteristics or preference but reflect a difference in the reconstructive options the patients have been offered. The Swedish healthcare system is almost solely public and there are very few private options. Hence, almost all patients get their primary surgical care at their local hospital, which could range from a small rural hospital to a major university hospital depending on where the patient lives. It is at the discretion of the surgeons at the local hospital to decide if the cases are best handled locally or if referral to a larger more experienced hospital is needed. There are no apparent financial incentives either to refer or not to refer. Where to refer for reconstructive IBD surgery is, in some, but not all regions, well defined and there is not yet any national coordination of reconstructive IBD surgery. We argue that this difference in the chance of receiving restored bowel continuity is most likely due to a lack of wide‐ranging reconstructive experience in some centres performing colectomies combined with a lack of well‐established referral routines.
Our findings confirm previous studies reporting that less than half of the Swedish patients undergo restorative surgery and that the proportion of patients receiving bowel continuity is greater in high‐volume hospitals [27, 33]. In the preliminary report from the ongoing CRUISE Study, the majority (80%) of the patients wish to undergo restorative surgery if they get the opportunity [34], indicating that unequal surgical treatment of IBD is present. In the present study, hospital IPAA volume was associated with the chance of having a pouch but not an IRA. These results were expected as IRA is a less technically advanced procedure. However, selecting the right patients can be challenging. IRA has a bad reputation internationally due to the risk of proctitis and rectal cancer [14, 35]. The observed increase in the use of IRA and corresponding decrease in the use of IPAA during the three time periods illustrate the reemergence of the IRA in Sweden, which has not been described in other countries.
The higher chance for an IPAA among men might be explained by the concern for reduced fertility for females after IPAA [36, 37]. There is reasonably good evidence that IRA does not further reduce fertility in females with UC subjected to colectomy [38, 39]. This would suggest a reciprocal increased chance for IRA among women, which we did not find, implying structural inequality from a gender perspective. An argument against structural inequality is that the possible effect of childbirth on the sphincter might refrain some women from opting for any reconstruction. Also, proctitis of the retained rectum in IRA might impair female sexual function, but there is, to our knowledge, no actual data to support this suggestion.
The objective of analysing the time from UC diagnosis to colectomy was to identify emergency colectomies and determine if emergency colectomy affected the chance of reconstruction. We will obviously not have identified all emergency colectomies this way since flairs later in the course of the disease may well render the need for emergency colectomy. Still, we think most, if not all, the colectomies performed within 30 days of the first UC diagnosis will have been emergency colectomies and hence it will represent a reasonable surrogate measure for emergency colectomy, knowing that it is not entirely reliable and many emergency colectomies will be missed from this definition. Our interpretation is thus that emergency colectomy is associated with a somewhat reduced chance for both IPAA and IRA. We had previously assumed it to be the other way around since at least IRA is reported to fare better in patients subjected to colectomy due to acute flair than refractory UC [16]. Our suggested explanation is, as previously stated, that most likely not all UC patients suitable for reconstruction are offered surgery.
Our finding that PSC was associated with an increased chance of getting an IRA is puzzling. This may reflect a different patient selection for reconstruction in the small volume hospital performing a larger proportion of IRA procedures, that is the patients are offered the locally available option rather than the best suited option. In the Swedish guidelines, PSC is a relative contraindication to IRA due to the further increased risk of CRC among UC patients with PSC [40, 41, 42]. Moreover, Block and colleagues reported a 53% failure rate after a median of 8 years follow‐up among PSC‐UC patients compared to only 22% among patients with only UC [43]. However, these findings were not confirmed by a national cohort study with up to 20 years of follow‐up [44].
We noted an increase in the use of IRA during the study period. Following the introduction of IPAA and the roughly contemporaneous attention to the increased cancer risk in patients undergoing IRA, the use of IRA declined in Sweden as well as in other countries. However, subsequent studies have shown that the increased cancer risk associated with IRA only becomes measurable after approximately 10 years [42, 45]. If patients with known elevated cancer risk (PSC and confirmed dysplasia/CRC) are carefully excluded, the long‐term risk remains acceptably low. Combined with favourable functional outcomes and a lesser impact on fertility, this has led to a renewed increase in the use of IRA in Sweden during the study period.
However, we anticipate that the proportion of IRA procedures will decline again, as modern medical therapy appears to select colectomy candidates in whom the rectum is more difficult to keep free of inflammation with topical 5‐ASA.
As expected, restorative surgery was more common in patients undergoing laparoscopic colectomy. Interestingly, a mediation analysis including mode of surgery yielded similar results as the main model indicating that the observed associations between hospital volume of IPAAs and the chance of restorative surgery cannot be explained by a more frequent use of minimal invasive surgery.
The foremost strength of this study is that it is population‐based with nationwide coverage, no loss to follow‐up and a long follow‐up time. The included registers have repeatedly shown to be reliable regarding diagnosis and surgical procedure codes [31, 46]. The greatest limitation is that we had no information on whether a permanent stoma was the choice of the patient or not, and if the patients received adequate information about the restorative procedures. Given the sole reliance on register data, we lacked reliable information on factors including disease severity, presence of low‐grade dysplasia, anal incontinence, referral patterns and if the patients actively opted against reconstruction, which may have affected the choice of restorative surgery. However, we do not believe that patients with contraindications to restorative surgery were more commonly treated at low‐volume hospitals given that patients with comorbidities and severe disease more commonly are treated at university hospitals.
Another limitation is that we might have underestimated the proportion of patients treated at low‐volume units that received an IPAA. Nowadays, the number of primary pouches is limited and primarily performed in those with dysplasia as an indication for colectomy, and in a few cases in patients with colorectal cancer where oncological treatment is not deemed needed. In the present study including surgeries since 1997, the number of primary IPAAs was larger in high than in low‐volume units. Some of these patients may have been referred from a low‐volume unit. However, the scope of the trial was to investigate whether it matters where the colectomy is performed, since that procedure has not been centralized yet [47]. This possible misclassification does not alter the interpretation of this study's findings, that is that the hospital that performs the colectomy is of importance for future restorative surgery with an IPAA.
CONCLUSION
This nationwide study of prospectively recorded data demonstrates the significance of hospital volume in pouch surgery, even at the time of colectomy. Patients who underwent colectomy at high‐volume centres were more likely to later receive a pouch. Future reorganization of care for inflammatory bowel disease should take this into account.
AUTHOR CONTRIBUTIONS
Anton Risto: Writing – original draft; writing – review and editing; methodology; investigation. Caroline Nordenvall: Conceptualization; methodology; writing – review and editing; project administration; supervision; investigation. Jonas Söderling: Formal analysis; writing – review and editing; methodology. Ola Olén: Conceptualization; methodology; writing – review and editing; data curation. Pär Myrelid: Conceptualization; writing – review and editing; supervision; methodology; investigation.
FUNDING INFORMATION
This project was supported by the agreement on Medical Training and Clinical Research between Region Östergötland and Linköping University and Region Stockholm and The Karolinska institute (the ALF agreement). Anton Risto received funds from ‘Mag‐Tarmfonden’ and the ‘SCUR’ fund.
CONFLICT OF INTEREST STATEMENT
None to declare.
ETHICS STATEMENT
Ethical approval was obtained from the ethical review board of the Stockholm region (2007/785‐31/5; 2011/1509‐32; 2012/601‐32, 2015/0004–31, 2015/615‐32, 2015/1030‐ 32, 2015/2237‐32, 2016/1929‐32, 2017/1959‐32).
Supporting information
Table S1.
Table S2.
Table S3.
Risto A, Myrelid P, Söderling J, Olén O, Nordenvall C. Chance of pouch surgery after colectomy for ulcerative colitis based on pelvic pouch volumes at the colectomy hospital, a Swedish national cohort study. Colorectal Dis. 2025;27:e70234. 10.1111/codi.70234
Proceedings: Presented at Swedish Surgical Society yearly meeting, Örebro 2023 and poster presentation at the Swedish Society of Gastroenterology, Linköping 2024.
DATA AVAILABILITY STATEMENT
Research data are not shared.
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Associated Data
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Supplementary Materials
Table S1.
Table S2.
Table S3.
Data Availability Statement
Research data are not shared.