- Email: [email protected]
Temporal changes in the management of diverticulitis
Journal of Surgical Research 124, 318 –323 (2005) doi:10.1016/j.jss.2004.11.005
Temporal Changes in the Management of Diverticulitis Leon Salem, M.D.,* Daniel A. Anaya, M.D.,* and David R. Flum, M.D., M.P.H.,*,†,1 *Department of Surgery and †Department of Health Services, University of Washington, Seattle, Washington Submitted for publication October 5, 2004
Purpose. This study was designed to evaluate temporal trends in the use and type of operative and non-operative interventions in the management of diverticulitis. Methods. A retrospective cohort using a statewide administrative database was used to identify all patients hospitalized for diverticulitis in the state of Washington (1987–2001). Poisson and logistic regression were used to calculate changes in the frequency of hospitalization, operative and percutaneous interventions, and colostomy over time. Results. Of the 25,058 patients hospitalized nonelectively with diverticulitis (mean age 69 ⴞ 16, 60% female) there were only minimal changes in the frequency of admissions over time (0.006% increase per year-IRR 1.00006 95% CI 1.00004, 1.00008). The odds of an emergency colectomy at initial hospitalization decreased by 2% each year (OR 0.98 95% CI 0.98, 0.99) whereas the odds of percutaneous abscess drainage increased 7% per year (OR 1.07 95% CI 1.05, 1.1). Among patients undergoing percutaneous drainage, the odds of operative interventions decreased by 9% compared to patients who did not have a percutaneous intervention (OR 0.91 95% CI 0.87, 0.94). The proportion of patients undergoing colostomy during emergency operations remained essentially stable over time (range 49 – 61%), as did the proportion of patients undergoing prophylactic colectomy after initial non-surgical management (⬃10%). Conclusions. There was a minimal increase in the frequency of diverticulitis admissions over time. A rise in percutaneous drainage procedures was associated with a decrease in emergency operative interventions. The proportion of patients undergoing colostomy remained stable, and there does not seem to be a signif-
icant increase in the use of one-stage procedures for diverticulitis. © 2005 Elsevier Inc. All rights reserved. Key Words: diverticulitis; colectomy; colostomy; outcomes; population-based. INTRODUCTION
Most data regarding diverticulitis management comes from single-institution case series and is therefore limited by selection and publication along with scope. Although there have been obvious changes in the management of diverticulitis over the last 20 years [computed tomography (CT) scanning, percutaneous drainage, better oral antibiotics and pain management, etc.] it is less clear to what extent these have impacted important outcomes. For example, there has been a growing body detailing primary resection and anastomosis [1, 2] in patients with diverticulitis as an alternative to Hartmann’s Procedure (HP). Over the same time period, primary anastomosis has become the standard of care in patients with traumatic perforations of the colon [3]. It is unclear to what extent primary anastomosis and colostomy avoidance has been incorporated into the care of patients with diverticulitis. The purpose of this study was to evaluate temporal trends in the use of surgical and percutaneous interventions in the management of diverticulitis. Specifically, our goal was to define operative management patterns in the population at large and given the trend toward primary anastomoses in other areas of colonic surgery, to test the hypothesis that the use of colostomy during non-elective operations has decreased over time. MATERIALS AND METHODS
1
To whom correspondence and reprint requests should be addressed at Department of Surgery, University of Washington, BB 431, 1959 N.E. Pacific St., Box 356410, Seattle, WA 98195-6410. E-mail: [email protected].
0022-4804/05 $30.00 © 2005 Elsevier Inc. All rights reserved.
A retrospective cohort study was conducted using a statewide, population-based hospital discharge database. Data were obtained from the Washington State Comprehensive Hospital Abstract Re-
318
319
SALEM ET AL.: TEMPORAL CHANGES IN DIVERTICULITIS MANAGEMENT porting System (CHARS) database. This dataset was derived from all public and private hospitals in Washington State, excluding Veterans Affairs (VA) and U.S. military hospitals. Error resulting from missing VA and military hospital patients was recognized but assumed to be stable over time. The dataset contains demographic variables, admission and discharge administrative details, payer status, ICD9 procedure and diagnosis codes, and coded hospital identifiers. CHARS records of interest were linked to the Washington State Department of Health Vital Statistics Database to identify patients who died during the follow-up period. United States census bureau data for yearly state population estimates were used for population-based analyses. This study was exempted from human subjects review by agreement of the University of Washington Human Subject Review Committee and the Washington State Department of Health. After linkage by patient identification number all patient identifiers are scrambled rendering this an anonymous dataset considered within the public domain.
Subjects We first determined the total number of colectomies [ICD9 procedure codes 45.73– 45.8) and colostomies (ICD9 procedure codes 46.1– 46.14)] in patients with diverticulitis (ICD9 diagnostic codes 562.11, 562.13). The cohort was then defined by searching all CHARS reports (1987–2001) for ICD9 diagnostic codes specific to diverticulitis (562.11 or 562.13). Patients under the age of 18, whose initial diverticulitis admission was for an elective procedure and those who also had a diagnosis of colon cancer were excluded.
Variable Definition The administrative designation of admission type was used to classify hospitalizations. Patients whose initial admission was characterized as not elective were considered in the analysis. When those patients also had concurrent ICD-9 procedure codes for colectomy and/or colostomy they were considered to have had emergency procedures. Those who did not undergo emergency procedures on their first admission for diverticulitis were defined as non-surgically treated. Percutaneous drainage was defined using the following ICD9 procedure codes (54.19, 70.12, and 54.91). A modified Charlson co-morbidity index [4] (0 –3, with 3 indicating greatest co-morbidity) was calculated for each patient based on ICD9 diagnostic codes.
Data Analysis Because population-based frequencies are sensitive to changes in the underlying population at risk, yearly population-based frequen-
cies of diverticulitis were also calculated. Employing the direct method, all data were standardized for sex and age using the 1990 population of Washington State as the reference. All populationbased frequencies were reported as a frequency per 100,000 people adjusted for age and sex. Poisson regression was used to test for a significant change over time in the frequency of diverticulitis admissions. A test for trend (i.e., the P value for whether the coefficient for calendar year was significantly different from 0) was applied to the frequencies of diverticulitis admissions, emergency and elective colectomies. The cohort was also divided into three 5-year periods and we compared demographic characteristics and treatment patterns among patients in each time period using univariate analysis. Changes in the use of colostomy were determined using logistic regression because of the relatively small number of cases. The association between patients undergoing percutaneous interventions and operative approaches was evaluated using logistic regression, adjusting for the age, sex, and comorbidity index of the patient. Statistical analysis was performed using STATA statistical analysis software, version 7 (STATA Corp, College Station, TX).
RESULTS
In the State of Washington between 1987 through 2001 there were 52,150 colon resections performed, 31.5% (n ⫽ 16,406) were for diverticulitis and its complications, including 53% of all sigmoid resections. Of the 14,326 colostomies performed during the same period 31.2% were associated with diverticular disease. The cohort included 25,058 (mean age 69 ⫾ 16, 60% female) patients non-electively hospitalized for diverticulitis. Changes over time in the characteristics of the population hospitalized with diverticulitis included; a decrease in the age from 67 ⫾ 15.2 to 65.3 ⫾ 16 in the first to last 5-year period (P ⬍ 0.001) and an increase in the percentage of the population that was male and had a higher comorbidity index (Table 1). There were only minimal changes in the standardized frequency of admissions for diverticulitis over time (0.006% increase per year-IRR 1.00006 95% CI 1.00004, 1.00008) with approximately 50 to 60 admissions per year for each 100,000 in the population. The percentage of patients undergoing an emergency colectomy at
TABLE 1 Changes in Demographic and Clinical Features of Diverticulitis Over Time
Age % female Charlson comorbidity index Mean length of stay, in days ⫾ SD Length of stay, in days (median) Likelihood of emergency surgery in initial admission Likelihood of stoma in initial admission Likelihood of stoma in operated patients Likelihood of percutaneous drainage Readmissions 30-day mortality
All
Time period 1 (1987–1991)
Time period 2 (1992–1996)
Time period 3 (1997–2001)
65.9 ⫾ 16.1 59.8% 0.4 ⫾ 0.8 6.1 ⫾ 6.3 4 19.6% 11% 56.2% 2.3% 19.0% 3.2%
67 ⫾ 15.2 62.1% 0.3 ⫾ 0.7 7.1 ⫾ 7.7 5 19.9 10.5% 52.6% 1.5% 20.9% 2.9%
65.7 ⫾ 16 59.6% 0.4 ⫾ 0.8 5.9 ⫾ 5.9 4 20.8% 12.1% 58.0% 2.0% 20.5% 3.0%
65.3 ⫾ 16 58.3% 0.5 ⫾ 0.8 5.3 ⫾ 5.3 4 18.5% 10.6% 57.3% 3.1% 16.5% 3.6%
P P P P P
⫽ ⬍ ⫽ ⫽
0.001 0.0001 0.0001 0.0001
P P P P P P
⫽ ⫽ ⫽ ⬍ ⬍ ⫽
0.001 0.002 0.005 0.0001 0.001 0.002
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initial hospitalization ranged from 17 to 22% and the odds of an initial emergency operation decreased by 2% each year (OR 0.98 95% CI 0.98, 0.99) once controlling for patient’s age and sex, and comorbidity index (Fig. 1). Conversely, after controlling for similar variables the odds of percutaneous abscess drainage increased by 7% per year (OR 1.07 95% CI 1.05, 1.1). Among patients undergoing percutaneous drainage (and adjusting for the age, sex, and comorbidity index), the frequency of operative interventions decreased by 9% (OR 0.91 95% CI 0.87, 0.94). This suggests that the rise in percutaneous procedures was associated with a decrease in operative interventions over time. The proportion of patients undergoing colostomy during emergency operations remained essentially stable over time (OR 0.99, 95% CI 0.99, 0.99) once adjusting for age, sex, and comorbidity index and ranged between 49% and 61%. As well, the frequency of colostomy concurrent to colectomy in elective cases did not vary significantly by year, averaging 15.9% and ranging from 13 to 20% (Fig. 2). There was a statistically significant, though clinically modest decrease in the odds per year of having an elective colectomy after initial non-operative management (OR 0.99, 95% CI 0.99, 0.99). This effect was identified for both patients under and over the age of 65, but in patients under 65 this was not a statistically significant effect (OR 0.99, 95% CI 0.99, 1.00). The rate of readmission after an initial episode of diverticulitis decreased over time from 20.9 to 16.5% (P ⬍ 0.01). Interestingly the rate of 30-day mortality in this cohort increased over time from 1.5 to 3.1% (P ⬍ 0.001). After adjusting for patient age, sex, and Charlson comorbidity index the odds of a 30-day death were not significantly greater over time (P ⫽ 0.13). DISCUSSION
This study sought to determine the patterns of patients with diverticulitis. Of all colectomies and colostomies performed nearly one-third were related to diverticulitis. Although diverticulitis is a leading indication for opera-
FIG. 1. Percentage of all initial, urgent/emergent for diverticulitis undergoing same-hospitalization colectomy or percutaneous abscess drainage, by year.
FIG. 2. Proportion of patients having concurrent colectomy with colostomy for diverticulitis, by admission status.
tive intervention, it is less clear if the incidence of this disease has increased over time. While smaller case series have suggested a surge in this entity, this study found only minimal increases in the incidence of hospitalizations for diverticulitis over the last 15 years. The proportion of admitted patients undergoing emergency operations decreased yearly concurrent to a 7% per year increase in the use of percutaneous drainage procedures. Interestingly, despite recent reports advocating primary anastomosis for patients with diverticular peritonitis, the percentage undergoing colostomy during non-elective operations did not decrease over time. Furthermore, despite reconsiderations of the need for prophylactic colectomy [5– 8], patterns of elective colectomy use did not change essentially over time with a stable frequency in patients both over and under age 50. There have been several recent reports suggesting an increase in the incidence of diverticulitis. Kang et al. [9] reported a 16% increase in the prevalence of diverticulitis admissions in England and an increase of 16% in the proportion undergoing operation over a 10-year period (1990 –2000). Interestingly, while the increase in the frequency found in our study was more modest (0.006% increase per year), the absolute prevalence was much higher in the United States (⬃60/ 100,000 versus ⬃25/100,000). The frequencies of diverticulitis across all years found in our study were very similar to those found in a national hospital discharge survey performed in the United States in 1987 [10] (53.3/100,000). The differences in absolute frequencies in the United States and in England may be linked to different thresholds for admission in various health systems, sociodemographic differences [11], and other cultural/ethnic components [12]. Alternatively, differences identified in the frequency of admissions may be explained by the means by which those frequencies were surveyed. We employed a rigorous analysis of age- and sex-standardized populations to better examine the effect of time on the frequencies of diverticulitis and found this effect to be negligible. The rate of readmission after an initial episode of diverticulitis decreased from 20.9 to 16.5% (P ⬍ 0.001). This may be
SALEM ET AL.: TEMPORAL CHANGES IN DIVERTICULITIS MANAGEMENT
related to a higher threshold of hospitalization and improved oral antibiotic treatment for diverticulitis. The availability of CT and interventional radiology to aid in the management of diverticulitis has increased dramatically over the last decade [13, 14]. Several reports have suggested that imaging technologies improve diagnostic accuracy [15] and outcome [16 –19] of patients with diverticulitis. Our evaluation of over 25,000 patients hospitalized with diverticulitis reports management trends in a period concurrent to the increasing availability of these technologies. We found that proportion of patients undergoing emergency surgery decreased slightly over time (⬃2% per year) whereas the frequency of percutaneous drainage increased ⬃7% per year. Whereas changes in disease severity may be a consideration [9, 20], experience with interventional radiology has increased and so has its effectiveness in converting operative candidates to non-operative candidates. It is less clear why other groups [9, 20] have identified increases in the proportion of patients with diverticulitis undergoing emergency surgery in the last decade. Although there has been little evidence to guide the timing of prophylactic colectomy recent modeled and non-modeled populationbased reports suggests that intervention after the 4th episode may be appropriate for most patients [21, 22]. Any increase in the trend towards delayed intervention may increase the rate of emergency colectomy. A growing number of investigators [23–27] report that primary anastomosis (PA) is a viable alternative to HP in diverticulitis, even in the presence of peritonitis. We found no decrease over time in the use of colostomy for non-elective operations. This lack of incorporation of the PA technique into common practice may be a result of misgivings about its safety and/or medicolegal concern. Alternatively, this finding may be the result of having a larger proportion of patients with more advanced disease, sepsis or hemodynamic instability who were not amenable to PA. The severity of diverticular disease and suitability for PA could not be assessed in our review. It should be noted, however, that our findings are similar to those of a populationbased study reported by Makela [20], in which 58% of 133 patients with perforated diverticulitis had a colostomy. Although there has never been a randomized prospective trial of HP and PA for patients with similar stage diverticulitis a recent collective review of this topic demonstrates that reported mortality and morbidity results for PA and HP are similar [28]. Intraoperative colonic lavage [29] has also been used to minimize the fecal load and has been shown to reduce intra-luminal bacterial content. Primary anastomosis with intraoperative lavage (PAIL) has also been advocated in the setting of advanced stage diverticulitis [1, 2, 30, 31].
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Lastly, this study examined trends in elective operative management. We found an essentially stable frequency of elective colectomy after an episode of medically treated diverticulitis. This may reflect the influence of the American Society of Colon and Rectal Surgeons (ASCRS) guidelines, suggesting elective colectomy after the first attack in patients younger than 50 and after the second episode in patients older than 50. These recommendations are based, however, on limited primary data and several recent reports indicate [7, 8] that younger patients are not at appreciably higher risk for adverse outcome and can be treated expectantly. Stable frequencies of elective surgery suggest that reports advocating a more limited role of prophylactic surgery have not impacted care patterns. There are several limitations to this study. The causes underlying stability or changes in frequencies over time cannot be discerned using retrospective techniques. For example, changes in the number of patients hospitalized for diverticulitis may not account for changes in disease severity over time. Alternatively, the threshold for hospitalizing a patient may have changed over time with the emergence of better oral antibiotics, increased outpatient management and cost containment. As a result, while the number of hospitalized patients with diverticulitis may have increased slightly over time, the number of patients with diverticulitis treated at home may have increased and those hospitalized now may be quite different in composition than those hospitalized 15 years ago. Assessments of temporal trends may therefore reflect changes in the population rather than changes in physician behavior. In fact, the comorbidity index of patients in this cohort did increase over time with a mean index of 0.3 (scale 0 –3, with 3 representing the highest level of comorbidity) from 1987 through 1990 to 0.5 in 1999 through 2002 (P ⬍ 0.001). We tried to assess this by controlling for patient comorbidity index over time in all analyses, but this was limited by a lack of diverticulitis-specific severity adjustment. Another limitation of assessing changes over time may be that better diagnostic imaging has changed the definition of a case. The number of patients diagnosed with diverticulitis likely increased because of the use of CT [32, 33], whereas in prior eras many patients with abdominal pain might have been classified with non-specific abdominal conditions. The statewide hospital discharge database for Washington State was not designed to be an operative database and therefore lacks elements of clinical importance that would have been helpful to further characterize the emergency admissions and elements that affected their outcome, such as disease severity, trial of intravenous antibiotic treatment, and the training level of the surgeon. The accuracy of the ICD-9 procedure coding in the CHARS
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database was previously evaluated by our group and found to be accurate for over 95% of ICD9 procedure codes [34, 35]. In conclusion, diverticulitis still accounts for nearly one-third of all colectomies and colostomies. The frequency of emergency operative intervention has decreased over time as the frequency of percutaneous drainage procedures has increased. Despite increasing evidence regarding the safety of primary anastomoses in diverticular peritonitis, the use of colostomy has not decreased over time. These temporal trends demonstrate the need for rigorous clinical trials to define the role of surgery and colostomy-sparing surgery in the treatment of diverticulitis (Fig. 1). Percentage of all initial, urgent/emergent admissions for diverticulitis undergoing the same-hospitalization colectomy or percutaneous abscess drainage, by year (Fig. 2). Proportion of patients having concurrent colectomy with colostomy for diverticulitis, by admission status. REFERENCES 1.
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SALEM ET AL.: TEMPORAL CHANGES IN DIVERTICULITIS MANAGEMENT M., Moreno, P., and Farran, L. Role of resection and primary anastomosis of the left colon in the presence of peritonitis. Br. J. Surg. 87: 1580, 2000. 31. Lee, E. C., Murray, J. J., Coller, J. A., Roberts, P. L., and Schoetz, D. J., Jr. Intraoperative colonic lavage in nonelective surgery for diverticular disease. Dis. Colon Rectum 40: 669, 1997. 32. Ambrosetti, P., Jenny, A., Becker, C., Terrier, T. F., and Morel, P. Acute left colonic diverticulitis— compared performance of computed tomography and water-soluble contrast enema: Prospective evaluation of 420 patients. Dis. Colon Rectum 43: 1363, 2000.
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Temporal Changes in the Management of Diverticulitis Leon Salem, M.D.,* Daniel A. Anaya, M.D.,* and David R. Flum, M.D., M.P.H.,*,†,1 *Department of Surgery and †Department of Health Services, University of Washington, Seattle, Washington Submitted for publication October 5, 2004
Purpose. This study was designed to evaluate temporal trends in the use and type of operative and non-operative interventions in the management of diverticulitis. Methods. A retrospective cohort using a statewide administrative database was used to identify all patients hospitalized for diverticulitis in the state of Washington (1987–2001). Poisson and logistic regression were used to calculate changes in the frequency of hospitalization, operative and percutaneous interventions, and colostomy over time. Results. Of the 25,058 patients hospitalized nonelectively with diverticulitis (mean age 69 ⴞ 16, 60% female) there were only minimal changes in the frequency of admissions over time (0.006% increase per year-IRR 1.00006 95% CI 1.00004, 1.00008). The odds of an emergency colectomy at initial hospitalization decreased by 2% each year (OR 0.98 95% CI 0.98, 0.99) whereas the odds of percutaneous abscess drainage increased 7% per year (OR 1.07 95% CI 1.05, 1.1). Among patients undergoing percutaneous drainage, the odds of operative interventions decreased by 9% compared to patients who did not have a percutaneous intervention (OR 0.91 95% CI 0.87, 0.94). The proportion of patients undergoing colostomy during emergency operations remained essentially stable over time (range 49 – 61%), as did the proportion of patients undergoing prophylactic colectomy after initial non-surgical management (⬃10%). Conclusions. There was a minimal increase in the frequency of diverticulitis admissions over time. A rise in percutaneous drainage procedures was associated with a decrease in emergency operative interventions. The proportion of patients undergoing colostomy remained stable, and there does not seem to be a signif-
icant increase in the use of one-stage procedures for diverticulitis. © 2005 Elsevier Inc. All rights reserved. Key Words: diverticulitis; colectomy; colostomy; outcomes; population-based. INTRODUCTION
Most data regarding diverticulitis management comes from single-institution case series and is therefore limited by selection and publication along with scope. Although there have been obvious changes in the management of diverticulitis over the last 20 years [computed tomography (CT) scanning, percutaneous drainage, better oral antibiotics and pain management, etc.] it is less clear to what extent these have impacted important outcomes. For example, there has been a growing body detailing primary resection and anastomosis [1, 2] in patients with diverticulitis as an alternative to Hartmann’s Procedure (HP). Over the same time period, primary anastomosis has become the standard of care in patients with traumatic perforations of the colon [3]. It is unclear to what extent primary anastomosis and colostomy avoidance has been incorporated into the care of patients with diverticulitis. The purpose of this study was to evaluate temporal trends in the use of surgical and percutaneous interventions in the management of diverticulitis. Specifically, our goal was to define operative management patterns in the population at large and given the trend toward primary anastomoses in other areas of colonic surgery, to test the hypothesis that the use of colostomy during non-elective operations has decreased over time. MATERIALS AND METHODS
1
To whom correspondence and reprint requests should be addressed at Department of Surgery, University of Washington, BB 431, 1959 N.E. Pacific St., Box 356410, Seattle, WA 98195-6410. E-mail: [email protected].
0022-4804/05 $30.00 © 2005 Elsevier Inc. All rights reserved.
A retrospective cohort study was conducted using a statewide, population-based hospital discharge database. Data were obtained from the Washington State Comprehensive Hospital Abstract Re-
318
319
SALEM ET AL.: TEMPORAL CHANGES IN DIVERTICULITIS MANAGEMENT porting System (CHARS) database. This dataset was derived from all public and private hospitals in Washington State, excluding Veterans Affairs (VA) and U.S. military hospitals. Error resulting from missing VA and military hospital patients was recognized but assumed to be stable over time. The dataset contains demographic variables, admission and discharge administrative details, payer status, ICD9 procedure and diagnosis codes, and coded hospital identifiers. CHARS records of interest were linked to the Washington State Department of Health Vital Statistics Database to identify patients who died during the follow-up period. United States census bureau data for yearly state population estimates were used for population-based analyses. This study was exempted from human subjects review by agreement of the University of Washington Human Subject Review Committee and the Washington State Department of Health. After linkage by patient identification number all patient identifiers are scrambled rendering this an anonymous dataset considered within the public domain.
Subjects We first determined the total number of colectomies [ICD9 procedure codes 45.73– 45.8) and colostomies (ICD9 procedure codes 46.1– 46.14)] in patients with diverticulitis (ICD9 diagnostic codes 562.11, 562.13). The cohort was then defined by searching all CHARS reports (1987–2001) for ICD9 diagnostic codes specific to diverticulitis (562.11 or 562.13). Patients under the age of 18, whose initial diverticulitis admission was for an elective procedure and those who also had a diagnosis of colon cancer were excluded.
Variable Definition The administrative designation of admission type was used to classify hospitalizations. Patients whose initial admission was characterized as not elective were considered in the analysis. When those patients also had concurrent ICD-9 procedure codes for colectomy and/or colostomy they were considered to have had emergency procedures. Those who did not undergo emergency procedures on their first admission for diverticulitis were defined as non-surgically treated. Percutaneous drainage was defined using the following ICD9 procedure codes (54.19, 70.12, and 54.91). A modified Charlson co-morbidity index [4] (0 –3, with 3 indicating greatest co-morbidity) was calculated for each patient based on ICD9 diagnostic codes.
Data Analysis Because population-based frequencies are sensitive to changes in the underlying population at risk, yearly population-based frequen-
cies of diverticulitis were also calculated. Employing the direct method, all data were standardized for sex and age using the 1990 population of Washington State as the reference. All populationbased frequencies were reported as a frequency per 100,000 people adjusted for age and sex. Poisson regression was used to test for a significant change over time in the frequency of diverticulitis admissions. A test for trend (i.e., the P value for whether the coefficient for calendar year was significantly different from 0) was applied to the frequencies of diverticulitis admissions, emergency and elective colectomies. The cohort was also divided into three 5-year periods and we compared demographic characteristics and treatment patterns among patients in each time period using univariate analysis. Changes in the use of colostomy were determined using logistic regression because of the relatively small number of cases. The association between patients undergoing percutaneous interventions and operative approaches was evaluated using logistic regression, adjusting for the age, sex, and comorbidity index of the patient. Statistical analysis was performed using STATA statistical analysis software, version 7 (STATA Corp, College Station, TX).
RESULTS
In the State of Washington between 1987 through 2001 there were 52,150 colon resections performed, 31.5% (n ⫽ 16,406) were for diverticulitis and its complications, including 53% of all sigmoid resections. Of the 14,326 colostomies performed during the same period 31.2% were associated with diverticular disease. The cohort included 25,058 (mean age 69 ⫾ 16, 60% female) patients non-electively hospitalized for diverticulitis. Changes over time in the characteristics of the population hospitalized with diverticulitis included; a decrease in the age from 67 ⫾ 15.2 to 65.3 ⫾ 16 in the first to last 5-year period (P ⬍ 0.001) and an increase in the percentage of the population that was male and had a higher comorbidity index (Table 1). There were only minimal changes in the standardized frequency of admissions for diverticulitis over time (0.006% increase per year-IRR 1.00006 95% CI 1.00004, 1.00008) with approximately 50 to 60 admissions per year for each 100,000 in the population. The percentage of patients undergoing an emergency colectomy at
TABLE 1 Changes in Demographic and Clinical Features of Diverticulitis Over Time
Age % female Charlson comorbidity index Mean length of stay, in days ⫾ SD Length of stay, in days (median) Likelihood of emergency surgery in initial admission Likelihood of stoma in initial admission Likelihood of stoma in operated patients Likelihood of percutaneous drainage Readmissions 30-day mortality
All
Time period 1 (1987–1991)
Time period 2 (1992–1996)
Time period 3 (1997–2001)
65.9 ⫾ 16.1 59.8% 0.4 ⫾ 0.8 6.1 ⫾ 6.3 4 19.6% 11% 56.2% 2.3% 19.0% 3.2%
67 ⫾ 15.2 62.1% 0.3 ⫾ 0.7 7.1 ⫾ 7.7 5 19.9 10.5% 52.6% 1.5% 20.9% 2.9%
65.7 ⫾ 16 59.6% 0.4 ⫾ 0.8 5.9 ⫾ 5.9 4 20.8% 12.1% 58.0% 2.0% 20.5% 3.0%
65.3 ⫾ 16 58.3% 0.5 ⫾ 0.8 5.3 ⫾ 5.3 4 18.5% 10.6% 57.3% 3.1% 16.5% 3.6%
P P P P P
⫽ ⬍ ⫽ ⫽
0.001 0.0001 0.0001 0.0001
P P P P P P
⫽ ⫽ ⫽ ⬍ ⬍ ⫽
0.001 0.002 0.005 0.0001 0.001 0.002
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initial hospitalization ranged from 17 to 22% and the odds of an initial emergency operation decreased by 2% each year (OR 0.98 95% CI 0.98, 0.99) once controlling for patient’s age and sex, and comorbidity index (Fig. 1). Conversely, after controlling for similar variables the odds of percutaneous abscess drainage increased by 7% per year (OR 1.07 95% CI 1.05, 1.1). Among patients undergoing percutaneous drainage (and adjusting for the age, sex, and comorbidity index), the frequency of operative interventions decreased by 9% (OR 0.91 95% CI 0.87, 0.94). This suggests that the rise in percutaneous procedures was associated with a decrease in operative interventions over time. The proportion of patients undergoing colostomy during emergency operations remained essentially stable over time (OR 0.99, 95% CI 0.99, 0.99) once adjusting for age, sex, and comorbidity index and ranged between 49% and 61%. As well, the frequency of colostomy concurrent to colectomy in elective cases did not vary significantly by year, averaging 15.9% and ranging from 13 to 20% (Fig. 2). There was a statistically significant, though clinically modest decrease in the odds per year of having an elective colectomy after initial non-operative management (OR 0.99, 95% CI 0.99, 0.99). This effect was identified for both patients under and over the age of 65, but in patients under 65 this was not a statistically significant effect (OR 0.99, 95% CI 0.99, 1.00). The rate of readmission after an initial episode of diverticulitis decreased over time from 20.9 to 16.5% (P ⬍ 0.01). Interestingly the rate of 30-day mortality in this cohort increased over time from 1.5 to 3.1% (P ⬍ 0.001). After adjusting for patient age, sex, and Charlson comorbidity index the odds of a 30-day death were not significantly greater over time (P ⫽ 0.13). DISCUSSION
This study sought to determine the patterns of patients with diverticulitis. Of all colectomies and colostomies performed nearly one-third were related to diverticulitis. Although diverticulitis is a leading indication for opera-
FIG. 1. Percentage of all initial, urgent/emergent for diverticulitis undergoing same-hospitalization colectomy or percutaneous abscess drainage, by year.
FIG. 2. Proportion of patients having concurrent colectomy with colostomy for diverticulitis, by admission status.
tive intervention, it is less clear if the incidence of this disease has increased over time. While smaller case series have suggested a surge in this entity, this study found only minimal increases in the incidence of hospitalizations for diverticulitis over the last 15 years. The proportion of admitted patients undergoing emergency operations decreased yearly concurrent to a 7% per year increase in the use of percutaneous drainage procedures. Interestingly, despite recent reports advocating primary anastomosis for patients with diverticular peritonitis, the percentage undergoing colostomy during non-elective operations did not decrease over time. Furthermore, despite reconsiderations of the need for prophylactic colectomy [5– 8], patterns of elective colectomy use did not change essentially over time with a stable frequency in patients both over and under age 50. There have been several recent reports suggesting an increase in the incidence of diverticulitis. Kang et al. [9] reported a 16% increase in the prevalence of diverticulitis admissions in England and an increase of 16% in the proportion undergoing operation over a 10-year period (1990 –2000). Interestingly, while the increase in the frequency found in our study was more modest (0.006% increase per year), the absolute prevalence was much higher in the United States (⬃60/ 100,000 versus ⬃25/100,000). The frequencies of diverticulitis across all years found in our study were very similar to those found in a national hospital discharge survey performed in the United States in 1987 [10] (53.3/100,000). The differences in absolute frequencies in the United States and in England may be linked to different thresholds for admission in various health systems, sociodemographic differences [11], and other cultural/ethnic components [12]. Alternatively, differences identified in the frequency of admissions may be explained by the means by which those frequencies were surveyed. We employed a rigorous analysis of age- and sex-standardized populations to better examine the effect of time on the frequencies of diverticulitis and found this effect to be negligible. The rate of readmission after an initial episode of diverticulitis decreased from 20.9 to 16.5% (P ⬍ 0.001). This may be
SALEM ET AL.: TEMPORAL CHANGES IN DIVERTICULITIS MANAGEMENT
related to a higher threshold of hospitalization and improved oral antibiotic treatment for diverticulitis. The availability of CT and interventional radiology to aid in the management of diverticulitis has increased dramatically over the last decade [13, 14]. Several reports have suggested that imaging technologies improve diagnostic accuracy [15] and outcome [16 –19] of patients with diverticulitis. Our evaluation of over 25,000 patients hospitalized with diverticulitis reports management trends in a period concurrent to the increasing availability of these technologies. We found that proportion of patients undergoing emergency surgery decreased slightly over time (⬃2% per year) whereas the frequency of percutaneous drainage increased ⬃7% per year. Whereas changes in disease severity may be a consideration [9, 20], experience with interventional radiology has increased and so has its effectiveness in converting operative candidates to non-operative candidates. It is less clear why other groups [9, 20] have identified increases in the proportion of patients with diverticulitis undergoing emergency surgery in the last decade. Although there has been little evidence to guide the timing of prophylactic colectomy recent modeled and non-modeled populationbased reports suggests that intervention after the 4th episode may be appropriate for most patients [21, 22]. Any increase in the trend towards delayed intervention may increase the rate of emergency colectomy. A growing number of investigators [23–27] report that primary anastomosis (PA) is a viable alternative to HP in diverticulitis, even in the presence of peritonitis. We found no decrease over time in the use of colostomy for non-elective operations. This lack of incorporation of the PA technique into common practice may be a result of misgivings about its safety and/or medicolegal concern. Alternatively, this finding may be the result of having a larger proportion of patients with more advanced disease, sepsis or hemodynamic instability who were not amenable to PA. The severity of diverticular disease and suitability for PA could not be assessed in our review. It should be noted, however, that our findings are similar to those of a populationbased study reported by Makela [20], in which 58% of 133 patients with perforated diverticulitis had a colostomy. Although there has never been a randomized prospective trial of HP and PA for patients with similar stage diverticulitis a recent collective review of this topic demonstrates that reported mortality and morbidity results for PA and HP are similar [28]. Intraoperative colonic lavage [29] has also been used to minimize the fecal load and has been shown to reduce intra-luminal bacterial content. Primary anastomosis with intraoperative lavage (PAIL) has also been advocated in the setting of advanced stage diverticulitis [1, 2, 30, 31].
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Lastly, this study examined trends in elective operative management. We found an essentially stable frequency of elective colectomy after an episode of medically treated diverticulitis. This may reflect the influence of the American Society of Colon and Rectal Surgeons (ASCRS) guidelines, suggesting elective colectomy after the first attack in patients younger than 50 and after the second episode in patients older than 50. These recommendations are based, however, on limited primary data and several recent reports indicate [7, 8] that younger patients are not at appreciably higher risk for adverse outcome and can be treated expectantly. Stable frequencies of elective surgery suggest that reports advocating a more limited role of prophylactic surgery have not impacted care patterns. There are several limitations to this study. The causes underlying stability or changes in frequencies over time cannot be discerned using retrospective techniques. For example, changes in the number of patients hospitalized for diverticulitis may not account for changes in disease severity over time. Alternatively, the threshold for hospitalizing a patient may have changed over time with the emergence of better oral antibiotics, increased outpatient management and cost containment. As a result, while the number of hospitalized patients with diverticulitis may have increased slightly over time, the number of patients with diverticulitis treated at home may have increased and those hospitalized now may be quite different in composition than those hospitalized 15 years ago. Assessments of temporal trends may therefore reflect changes in the population rather than changes in physician behavior. In fact, the comorbidity index of patients in this cohort did increase over time with a mean index of 0.3 (scale 0 –3, with 3 representing the highest level of comorbidity) from 1987 through 1990 to 0.5 in 1999 through 2002 (P ⬍ 0.001). We tried to assess this by controlling for patient comorbidity index over time in all analyses, but this was limited by a lack of diverticulitis-specific severity adjustment. Another limitation of assessing changes over time may be that better diagnostic imaging has changed the definition of a case. The number of patients diagnosed with diverticulitis likely increased because of the use of CT [32, 33], whereas in prior eras many patients with abdominal pain might have been classified with non-specific abdominal conditions. The statewide hospital discharge database for Washington State was not designed to be an operative database and therefore lacks elements of clinical importance that would have been helpful to further characterize the emergency admissions and elements that affected their outcome, such as disease severity, trial of intravenous antibiotic treatment, and the training level of the surgeon. The accuracy of the ICD-9 procedure coding in the CHARS
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database was previously evaluated by our group and found to be accurate for over 95% of ICD9 procedure codes [34, 35]. In conclusion, diverticulitis still accounts for nearly one-third of all colectomies and colostomies. The frequency of emergency operative intervention has decreased over time as the frequency of percutaneous drainage procedures has increased. Despite increasing evidence regarding the safety of primary anastomoses in diverticular peritonitis, the use of colostomy has not decreased over time. These temporal trends demonstrate the need for rigorous clinical trials to define the role of surgery and colostomy-sparing surgery in the treatment of diverticulitis (Fig. 1). Percentage of all initial, urgent/emergent admissions for diverticulitis undergoing the same-hospitalization colectomy or percutaneous abscess drainage, by year (Fig. 2). Proportion of patients having concurrent colectomy with colostomy for diverticulitis, by admission status. REFERENCES 1.
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