Abstract
Background
The management of perforated diverticular disease has changed in the past 10 years with a move towards less surgical intervention. This population-based cohort study aimed to define the risk of death and readmission following non-operative management of perforated diverticular disease.
Methods
Patients diagnosed with perforated diverticular disease and managed without surgery were identified from the linked Clinical Practice Research Datalink and Hospital Episode Statistics data from 2000 to 2013. The outcomes were 1-year case fatality, readmissions, and surgery at readmission.
Results
In total, 880 patients with perforated diverticular disease were managed without surgery, comprising 523 women (59.4 per cent). The 1-year case fatality rate was 33.2 per cent (293 of 880). The majority of deaths occurred in the first 90 days after the index admission, with a 90-day case fatality rate of 28.8 per cent. The 90-day survival rate varied by age, and was 97.2 per cent among those aged less than 65 years, compared with 85.0 per cent for those aged between 65 and 74 years, and 47.7 per cent in those at least 75 years old. Of 767 patients discharged from hospital, 250 (32.6 per cent) were readmitted (47 elective, 6.1 per cent; 203 emergency, 26.5 per cent) during a median of 1.6 (i.q.r. 0.1–3.9) years of follow-up, with similar proportions in each age category. In the first year of follow-up, only 5.1 per cent of patients required surgery, of whom 16 of 767 (2.1 per cent) required elective and 23 (3.0 per cent) emergency operation.
Conclusion
Non-operative management of perforated diverticulitis in those aged less than 65 years is feasible and safe. Reintervention rates following conservative management were low across all age categories.
Among patients treated conservatively for perforated diverticulitis, 32.6 per cent of those discharged from hospital required emergency readmission during follow-up. Of these, only 3.0 per cent required emergency surgery. Reintervention rates after conservative management of perforated diverticular disease are reassuringly low.
Resumen
Antecedentes
El tratamiento de la enfermedad diverticular perforada ha cambiado en los últimos 10 años con una tendencia hacia un menor porcentaje de intervenciones quirúrgicas. Este estudio de cohortes de base poblacional tuvo como objetivo definir el riesgo de mortalidad y de reingreso después del tratamiento no quirúrgico de la enfermedad diverticular perforada (diverticular disease, DD).
Métodos
Los pacientes diagnosticados con DD perforada y tratados sin cirugía se identificaron a partir de los datos vinculados del Clinical Practice Research Datalink y del Hospital Episode Statistics de 2000 a 2013. Las variables de interés eran la tasa de letalidad a 1 año, los reingresos y la cirugía durante el reingreso.
Resultados
En total, 880 pacientes con DD perforada fueron tratados sin cirugía, entre ellos 523 mujeres (59,4%). La letalidad a 1 año fue del 33,2% (293/880). La mayoría de las muertes ocurrieron en los primeros 90 días después del primer ingreso con una letalidad a los 90 días del 28,8%. La supervivencia a los 90 días varió según la edad, con un 97,2% de supervivencia a los 90 días en los pacientes de menos de 65 años de edad en comparación con un 85,0% en los de 65 a 74 años y un 47,7 % en los mayores de 75 años. De 767 pacientes dados de alta del hospital, 250 (32,6%, 250/767) fueron reingresados, (47 programados (6,1%) y 203 reingresos urgentes (26,5%)) durante una mediana de 1,6 años de seguimiento (rango intercuartílico 0,1-3,9 años) con proporciones similares en cada categoría de edad. En el primer año de seguimiento solo el 5,1% de los pacientes requirieron cirugía, de los cuales 16/767 (2,1%) requirieron cirugía programada y 23/767 (3,0%) urgente.
Conclusión
El tratamiento conservador de la diverticulitis perforada en pacientes de menos de 65 años de edad es factible y seguro. Las tasas de reintervención después de un tratamiento conservador fueron bajas en todas las franjas de edad.
Introduction
Perforation is the most severe complication of diverticular disease and is becoming more common1–3. It is associated with significant mortality and surgical intervention is associated with significant morbidity4. An epidemiological study of Scottish National Health Service (NHS) hospitals reported an increase in annual emergency admissions for complicated diverticular disease from 22.9 per cent in 2000 to 27.1 per cent in 2010; this was associated with a decrease in the number of patients undergoing emergency surgery, suggesting that a greater proportion were being treated conservatively5. This change towards non-operative management is also acknowledged in recent UK professional guidelines6. Emerging evidence7 suggests that patients with diverticulitis and localized perforation can be managed successfully with a non-operative approach7–11. Evidence that informs this practice, however, reflects single-centre observational studies, small patient numbers, and often short-term outcomes8–11. Important patient-level risk factors and confounders for treatment failure, such as age, sex and co-morbidity, could not be explored with any precision, and there was also a high risk of selection bias.
There is a dearth of large population-based studies evaluating outcomes after conservative management of perforated diverticulitis. The natural history of patients with perforated diverticulitis who are managed conservatively in terms of disease recurrence, readmission rates, need for surgery, and mortality are poorly reported. This population-based cohort study evaluated these outcomes after non-operative management of perforated diverticular disease using healthcare data from England.
Methods
This study was conducted and reported according to recommendations laid out in the STROBE checklist12. It received approval from the Independent Scientific Advisory Committee approval board, which provides scientific advice to the Medicines and Healthcare products Regulatory Agency (MHRA) on study design, and advised whether further approval was required from the Multi-centre Research Ethics Committee outside the MHRA’s current approval for observational studies (Protocol 16_226R).
Study design
Two previously well characterized databases were used13,14. The Clinical Practice Research Datalink (CPRD) contains diagnostic and prescription data for over 14.1 million of the general population in the UK, with 3.4 million active patients contributing data13,14. Data are audited regularly with participating general practices, with quality checks to ensure that data are up to standard for research purposes. Hospital Episode Statistics (HES) is a data source containing detailed records of each episode of admitted patient care delivered in England either by NHS hospitals, or commissioned by the NHS but delivered in the independent sector1. Patient records in HES are coded using a combination of the ICD-10 codes for diagnoses at discharge, and OPCS-4 codes for the relevant procedure undertaken during that admission1,13,14.
Validation
Because of the dependence on the accuracy of primary-care records, a two-stage approach described by Humes and colleagues1 was used to validate the case definition of perforated diverticulitis. This included a local audit of patients diagnosed with an ICD-10 code of K57.2 (diverticular disease of large intestine with perforation and abscess) and K57.8 (diverticular disease of intestine, part unspecified, with perforation and abscess). A sample of anonymized case records of patients classed as having perforated diverticulitis was also subsequently validated1. These definitions of perforated diverticulitis and diverticulitis associated with an abscess have been used in subsequent work in complicated diverticular disease13.
Study group
All patients with an incident diagnosis of perforated diverticular disease were identified, who had a Read or Oxford Medical Information Systems code, or ICD-10 code for perforation due to colonic diverticular disease between 2000 and 2013. All patients with a code for colorectal cancer (C18–C21) were excluded. A case was defined as incident if no previous record of perforated colonic diverticular disease was entered in the patient’s record within 90 days of original registration at the patient’s general practice, as used elsewhere15. OPCS codes from HES data were used to identify patients with perforated diverticulitis who had undergone surgical resection. Patients without a surgical intervention during the index admission were considered to have been treated non-operatively and formed the study group.
Co-variables
Age was subclassified as less than 65 years, 65–74 years, and 75 years or more. Co-morbidity was classified using the Charlson’s Co-morbidity Index16 as 0 or 1 or more, as identified from Read and ICD codes before the index admission. Smoking status was classified as never or ever smoked, based on CPRD records before operation. BMI before surgery was extracted from primary-care data, and categorized into four groups as: normal (BMI 18.5-24.9 kg/m2); underweight (BMI<18.5 kg/m2) and overweight (BMI 25-29.9 kg/m2); obese (BMI ≥30 kg/m2); or missing. Patients were followed up from the incident date of perforated diverticular disease diagnosis until date of death, end of available follow-up, or for 1 year. The 30-day, 90-day, and 1-year mortality rates were determined based on death registrations from Office for National Statistics data1. Duration of hospital stay and readmission data were determined for all patients who were alive at discharge (calculated as the difference between total number of patients and in-hospital deaths). Type of readmission at 1 year was classified as elective or emergency, and operative procedures at readmission were similarly grouped as emergency or elective colectomy.
Statistical analysis
Demographic characteristics are reported using frequencies and percentages along with median age and duration of hospital stay. Case fatality was calculated as the number of deaths per each age-category at 30-days, 90-days and 1-year. A Cox proportional hazards model was fitted to estimate the hazard ratio for mortality. Patients were entered at the date of incident diagnosis of perforated diverticular disease, and were censored at the date on which death was recorded, they transferred out of the participating general practice, the practice was no longer deemed up to standard, or at 1 year after diagnosis, whichever was earliest. The analysis was adjusted for potential a priori confounders (age, sex, co-morbidity). The proportional hazards of the final models were checked using log-log plots. All analysis was performed using Stata/MP® version 15 (StataCorp, College Station, Texas, USA).
Results
A total of 2347 patients were identified who had an incident diagnosis of perforated diverticular disease. Of these, 880 were managed without surgery and formed the study population (Fig. 1). There were 523 women (59.4 per cent). Median age was 75 (i.q.r. 59–85) years. The proportion of the population aged 65 years or older was 67.4 per cent (593 patients). Demographic characteristics of patients in the study are summarized in Table 1 and Table S1.
Fig. 1.
Study flow diagram
Table 1.
Baseline demographics of patients with conservatively managed perforated diverticular disease
| Entire cohort | Survivors | Non-survivors | P † | |
|---|---|---|---|---|
| (n = 880) | (n = 767) | (n = 113) | ||
| Age (years) | < 0.001 | |||
| 18–64 | 287 (32.6) | 285 (37.2) | –* | |
| 65–74 | 162 (18.4) | 154 (20.1) | –* | |
| ≥ 75 | 431 (49.0) | 328 (42.8) | 103 (91.2) | |
| Sex ratio (M : F) | 357 : 523 | 327 : 440 | 30 : 83 | 0.001 |
| Co-morbidity | 0.008 | |||
| None | 412 (46.8) | 373 (48.6) | 39 (34.5) | |
| ≥1 | 468 (53.2) | 394 (51.4) | 74 (65.5) | |
| BMI category | 0.017 | |||
| Normal weight | 248 (28.2) | 218 (28.4) | 30 (26.5) | |
| Overweight or underweight | 277 (31.5) | 238 (31.0) | 39 (34.5) | |
| Obese | 236 (26.8) | 216 (28.2) | 20 (17.7) | |
| Missing | 119 (13.5) | 95 (12.4) | 24 (21.2) | |
| Smoking status | ||||
| Non-smoker | 318 (36.1) | 267 (34.8) | 51 (45.1) | 0.007 |
| Ever smoker | 529 (60.1) | 475 (61.9) | 54 (47.8) | |
| Missing | 33 (3.8) | 25 (3.3) | 8 (7.1) | |
Values in parentheses are percentages. *Cell count too low to report. †Chi square test.
In-hospital mortality
The in-hospital mortality rate was 12.8 per cent (113 of 880); patients aged 75 years or older accounted for 103 in-hospital deaths (91.2 per cent). The total number of patients who survived to discharge and were at risk of readmission was 767.
Duration of hospital stay
The overall median total duration of stay was 4 (i.q.r. 1–8) days. There was no significant difference in median length of stay by age categories.
Case fatality and survival at 30 days, 90 days, and 1 year
The 30-day survival rate was 98.3 (95 per cent c.i. 95.8 to 99.3) per cent overall, and 57.7 (52.9 to 62.2) per cent among those aged 75 years or more. The case fatality rate at 30 days was 1.7 per cent in those younger than 65 years, representing an 80 per cent reduction in risk of death compared with those aged 65–74 years (adjusted HR 0.17, 95 per cent c.i. 0.06 to 0.46). Among patients aged 75 years or more, there was a nearly five-fold increase in risk of death at 30 days compared with those aged 65–74 years (case fatality rate 42.2 per cent; adjusted HR 4.64, 95 percent c.i. 2.81 to 7.64) (Table 2)
Table 2.
Survival and adjusted hazard ratios for death at 30 days, 90 days, and 1 year after management of perforated diverticulitis
| Case fatality rate* | Survival (%)† | Unadjusted HR† | Adjusted HR†‡ | |
|---|---|---|---|---|
| 30 days | ||||
| 18–64 | 5 of 287 (1.7) | 98.3 (95.8, 99.3) | 0.16 (0.06-0.43) | 0.17 (0.06-0.46) |
| 65–74 | 17 of 162 (10.5) | 89.5 (83.6, 93.3) | 1.00 (reference) | 1.00 (reference) |
| ≥ 75 | 182 of 431 (42.2) | 57.7 (52.9, 62.2) | 4.86 (2.96-8.00) | 4.64 (2.81-7.64) |
| 90 days | ||||
| 18–64 | 8 of 287 (2.8) | 97.2 (94.4, 98.6) | 0.18 (0.08-0.39) | 0.19 (0.08-0.42) |
| 65–74 | 24 of 162 (14.8) | 85.0 (78.5, 89.7) | 1.00 (reference) | 1.00 (reference) |
| ≥ 75 | 222 of 431 (51.5) | 47.7 (42.9, 52.4) | 4.50 (2.95-6.86) | 4.31 (2.82-6.58) |
| 1 year | ||||
| 18–64 | 10 of 287 (3.5) | 96.3 (93.3, 98.0) | 0.17 (0.09-0.36) | 0.19 (0.09-0.39) |
| 65–74 | 30 of 162 (18.5) | 81.0 (73.9, 86.3) | 1.00 (reference) | 1.00 (reference) |
| ≥ 75 | 253 of 431 (58.7) | 39.2 (34.5, 43.8) | 4.39 (3.00-6.41) | 4.17 (2.85-6.10) |
Values in parentheses are *percentages and †95 per cent confidence intervals. Hazard ratios (HRs) were calculated using Cox proportional hazards model. ‡Adjusted for age, sex, and co-morbidity (defined using Charlson’s Co-morbidity Index).
A similar relationship was seen at 90 days. The Kaplan–Meier survival curve confirmed that the majority of deaths occurred within 90 days of the initial admission (Fig. 2). At 1 year, the survival rate was 96.3 (93.3 to 98.0) per cent in those younger than 65 years, but only 39.2 (34.5 to 43.8) among those aged 75 years and over (Table 2 and Table S2).
Fig. 2.
Kaplan–Meier survival estimates at 1 year by age category
No relationship was found between BMI and mortality at any time point.
Readmission
A total of 767 of 880 patients survived to discharge. One-third of these patients (250 of 767, 32.6 per cent) were readmitted during a median of 1.6 (i.q.r. 0.1–3.9) years of follow-up, including 47 elective readmissions (18.8 per cent) and 203 (81.2 per cent) emergency readmissions for recurrence or complications related to diverticular disease. Of all patients readmitted, 154 of 250 (61.6 per cent) were admitted once (Fig. 3).
Fig. 3.
Total diverticular disease-related readmissions during total follow-up.
Median follow-up was 1.6 years and longest follow-up 14.2 years. A total of 250 patients were readmitted during total follow-up. 154 patients were readmitted only once, and nine patients had six or more readmissions during total follow-up.
A similar proportion of patients was readmitted across the different age categories during the entire follow-up period. Some 96 of 285 patients (33.7 per cent) were readmitted in the 18–64-year group, 50 of 154 (32.5 per cent) in the 65–74-year group, and 104 of 328 (31.7 per cent) aged over 75 years.
In multivariable cox regression analysis, only co-morbidity was associated with an increased risk of readmission at 1 year of follow-up (Table S3). Importantly, no relationship was identified between readmission and BMI.
First-year readmission, operative procedures, and duration of stay
In the first year after the index admission, 173 of the 767 patients who survived to discharge were readmitted (22.6 per cent). This included 65 of 285 patients (22.8 per cent) aged 18–64 years, 28 of 154 (18.2 per cent) in the 65–74-year group, and 80 of 328 (24.4 per cent) aged 75 years or more (Table 3).
Table 3.
Readmissions and surgery during the first year after index admission with conservatively managed perforated diverticulitis
| 18–64 years | 65–74 years | ≥ 75 years | Total | |
|---|---|---|---|---|
| First-year readmissions | n = 285 | n = 154 | n = 328 | n = 767 |
| Total | 65 (22.8) | 28 (18.2) | 80 (24.4) | 173 (22.6) |
| Elective readmission | 15 (5.3) | 7 (4.5) | 10 (3.0) | 32 (4.2) |
| Emergency readmission | 50 (17.5) | 21 (13.6) | 70 (21.3) | 141 (18.4) |
| First-year surgery at readmission | n = 285 | n = 482* | n = 767 | |
| Total | 21 (7.4) | 18 (3.7) | 39 (5.1) | |
| Elective surgery | 10 (3.5) | 6 (1.2) | 16 (2.1) | |
| Emergency surgery | 11 (3.9) | 12 (2.5) | 23 (3.0) | |
*Owing to reporting guidelines regarding cell numbers, the total number of operations in the two older groups have been combined to allow reporting of operative interventions in these patients.
Emergency admission was the predominant type of readmission. There were 50 emergency and 15 elective readmissions in the 18–64-year group, 21 emergency and seven elective admissions in the 65–74-year group, and 70 emergency and 10 elective admissions among patients aged 75 years or more.
In the first year of follow-up, 16 of 767 patients (2.1 per cent) underwent emergencies elective surgery and 23 (3.0 per cent) emergency surgery during readmission. Among those aged 18–64 years, 10 of 285 (3.5 per cent) underwent elective surgery and another 11 (3.9 per cent) had an emergency operation. Owing to the limited number of operative interventions in the two older groups, the data are reported together for 482 patients aged at least 65 years. Of these, only six (1.2 per cent) underwent elective surgery and 12 (2.5 per cent) emergency surgery in the first year of follow-up (Table 3). Among these 18 patients, 11 operations were Hartmann’s procedures and none were reversed.
Median duration of stay on readmission (with or without surgery) was 6 (i.q.r. 2–10) days overall, 5 (2–9) days for patients admitted electively and 6 (3–10) days for those admitted as an emergency.
Discussion
In patients younger than 65 years, conservatively management of perforated diverticulitis is safe and associated with a low risk of death both in the short (30 days) and longer (1 year) term. The in-hospital mortality rate of 12.8 per cent was predominantly accounted for by those aged 75 years (91.2 per cent of in-hospital deaths) and these patients had a proportionally higher case fatality rate at 30 days, 90 days, and 1 year. These results suggest that those of advanced age with co-morbidity may have been considered unfit for surgery and managed non-operatively on that basis. The data sources used did not include information on this aspect of decision-making.
One-third of all patients who survived the index admission were readmitted during the entire follow-up and this did not vary by age. The majority of readmissions occurred within the first year of index admission and 81.5 per cent of these readmissions (141 of 173) were as an emergency, although only small proportion of patients (5.1 per cent) needed surgery as a result of readmission in the first year. This suggests that, in the short term, conservative management of locally perforated diverticular disease is safe, but the patient must be informed of the risk of subsequent readmissions, especially in the first year.
Two population-based studies5,17 have reported a trend away from surgical intervention in the management of perforated diverticular disease. The proportion of patients undergoing surgical intervention for emergency admissions with diverticular disease fell from a peak of 16.3 per cent in 2002 to 11.5 per cent in 2010 in Scotland5, and from 17 to 14 per cent in the USA17. This decline in use of surgery and increase in conservative management was not thought to be a result of less severe disease, but considered to reflect better supportive care and more accurate selection of patients, potentially influenced by the availability of and improvements in high-resolution CT5. The majority of nationwide clinical guidelines now recommend CT to confirm and grade the severity of acute diverticular disease18 and to guide management19.
Four observational studies have suggested non-operative management of perforated diverticulitis to be safe. These small single-centre studies had total numbers of 399, 6410, 1328, and 136 patients11 respectively. Follow-up was limited, and none explored the impact of age and co-morbidity on findings. One study10, however, found that ASA grade III and IV, and distant location of air, were the two predictors of failure of non-operative treatment, whereas another11 reported a high success rate of conservative treatment in patients with perforated diverticulitis and pneumoperitoneum who were haemodynamically stable. Sallinen and colleagues8 described the feasibility of conservative management in haemodynamically stable patients with pericolic extraluminal air or a small amount of distant intraperitoneal air in the absence of clinical diffuse peritonitis. No study reported on readmission or subsequent need for surgical intervention.
A study from New Zealand reported on patterns of readmission after an initial admission with complicated or uncomplicated diverticulitis, and found an overall recurrence rate of 24 per cent in patients with complicated diverticulitis (abscess and perforation), with the majority of readmissions occurring in the first year after index presentation20. As in the present study, no difference was found in recurrence between young (aged less than 50 years) and older patients20.
The present study was reliant on coding databases with a risk of misclassification. This approach also did not allow a useful predictor, such as extent of intraperitoneal contamination, to be considered as a factor determining the success of non-operative management7,19. BMI has been shown recently to be associated with an increased risk of perforated diverticulitis and readmission; however, in the present study, although a majority (60 per cent) of patients had an abnormal BMI (overweight or obese), this was not predictive of death or readmission in Cox regression analysis. This could have been influenced by the incompleteness of BMI data (13.5 per cent missing data).
The methodology used here, however, is based on a previously validated approach1 for confirmation of the diagnosis of perforated diverticulitis in the HES and CPRD linked data sets. The ability to describe mortality rates by age group, risk of readmission, and low rates of surgery should readmission be necessary, provides reassurance to surgeons and better information to patients in shared decision-making.
Funding
The work was funded by CORE grant awarded to D.J.H.
Disclosure: The authors declare no conflict of interest. The funders had no role in the study design, data analysis or presentation of findings.
Supplementary material
Supplementary material is available at BJS Open online.
Supplementary Material
References
- 1. Humes DJ, Solaymani-Dodaran M, Fleming KM, Simpson J, Spiller RC, West J.. A population-based study of perforated diverticular disease incidence and associated mortality. Gastroenterology 2009;136:1198–1205 [DOI] [PubMed] [Google Scholar]
- 2. Mäkelä J, Kiviniemi H, Laitinen S.. Prevalence of perforated sigmoid diverticulitis is increasing. Dis Colon Rectum 2002;45:955–961 [DOI] [PubMed] [Google Scholar]
- 3. Strate LL, Morris AM.. Epidemiology, pathophysiology, and treatment of diverticulitis. Gastroenterology 2019;156:1282e.1–1298.e1 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Weizman AV, Nguyen GC.. Diverticular disease: epidemiology and management. Can J Gastroenterol 2011;25:385–389 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Paterson HM, Arnott ID, Nicholls RJ, Clark D, Bauer J, Bridger PC. et al. Diverticular disease in Scotland: 2000–2010. Colorectal Dis 2015;17:329–334 [DOI] [PubMed] [Google Scholar]
- 6. National Institute for Health and Care Excellence . Guidance 147, Management of Diverticular Disease. https://pathways.nice.org.uk/pathways/diverticular-disease (accessed 10 December 2020).
- 7. Sartelli M, Catena F, Ansaloni L, Coccolini F, Griffiths EA, Abu-Zidan FM. et al. WSES guidelines for the management of acute left sided colonic diverticulitis in the emergency setting. World J Emerg Surg 2016;11:37. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Sallinen VJ, Mentula PJ, Leppäniemi AK.. Nonoperative management of perforated diverticulitis with extraluminal air is safe and effective in selected patients. Dis Colon Rectum 2014;57:875–881 [DOI] [PubMed] [Google Scholar]
- 9. Costi R, Cauchy F, Le Bian A, Honart JF, Creuze N, Smadja C.. Challenging a classic myth: pneumoperitoneum associated with acute diverticulitis is not an indication for open or laparoscopic emergency surgery in hemodynamically stable patients. A 10-year experience with a nonoperative treatment. Surg Endosc 2012;26:2061–2071 [DOI] [PubMed] [Google Scholar]
- 10. Titos-Garcia A, Aranda-Narvaez JM, Romacho-Lopez L, Gonzalez-Sanchez AJ, Cabrera-Serna I, Santoyo-Santoyo J.. Nonoperative management of perforated acute diverticulitis with extraluminal air: results and risk factors of failure. Int J Colorectal Dis 2017;32:1503–1507 [DOI] [PubMed] [Google Scholar]
- 11. Dharmarajan S, Hunt SR, Birnbaum EH, Fleshman JW, Mutch MG.. The efficacy of nonoperative management of acute complicated diverticulitis. Dis Colon Rectum 2011;54:663–671 [DOI] [PubMed] [Google Scholar]
- 12. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP.. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet 2007;370:1453–1457 [DOI] [PubMed] [Google Scholar]
- 13. Humes DJ, West J.. Role of acute diverticulitis in the development of complicated colonic diverticular disease and 1-year mortality after diagnosis in the UK: population-based cohort study. Gut 2012;61:95. [DOI] [PubMed] [Google Scholar]
- 14. Adiamah A, Ban L, West J, Humes DJ.. The risk of venous thromboembolism after surgery for esophagogastric malignancy and the impact of chemotherapy: a population-based cohort study. Dis Esophagus 2019;33:doz079. [DOI] [PubMed] [Google Scholar]
- 15. Lewis JD, Bilker WB, Weinstein RB, Strom BL.. The relationship between time since registration and measured incidence rates in the General Practice Research Database. Pharmacoepidemiol Drug Saf 2005;14:443–451 [DOI] [PubMed] [Google Scholar]
- 16. Charlson ME, Pompei P, Ales KL, MacKenzie CR.. A new method of classifying prognostic comorbidity in longitudinal studies: Development and validation. J Chronic Dis 1987;40:373–383 [DOI] [PubMed] [Google Scholar]
- 17. Etzioni DA, Mack TM, Beart RW Jr, Kaiser AM.. Diverticulitis in the United States: 1998–2005: changing patterns of disease and treatment. Ann Surg 2009;249:210–217 [DOI] [PubMed] [Google Scholar]
- 18. Fozard JBJ, Armitage NC, Schofield JB, Jones OM.. ACPGBI position statement on elective resection for diverticulitis. Colorectal Dis 2011;13:1–11 [DOI] [PubMed] [Google Scholar]
- 19. Sartelli M, Moore FA, Ansaloni L, Di Saverio S, Coccolini F, Griffiths EA. et al. A proposal for a CT driven classification of left colon acute diverticulitis. World J Emerg Surg 2015;10:3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20. Eglinton T, Nguyen T, Raniga S, Dixon L, Dobbs B, Frizelle FA.. Patterns of recurrence in patients with acute diverticulitis. Br J Surg 2010;97:952–957 [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.