Trends in diverticular disease mortality among United States adults (1999–2020) by gender, race, and geographic region

Abstract

BACKGROUND

Diverticular disease of the intestine is a major gastrointestinal cause of mortality in the United States and the world. It is one of the most common gastrointestinal conditions responsible for hospital admissions.

AIM

To identify mortality trends of diverticular disease among adults in the United States, examining regional and demographic variations, as these have not been previously studied. These trends are highly beneficial to studying disease burden and vulnerable populations.

METHODS

Diverticular disease-related mortality data were extracted as age-adjusted mortality rates (AAMRs) from death certificate data of the CDC WONDER database using International Statistical Classification of Diseases and Related Health Problems-10^th Revision codes K57.0 to K57.9 from 1999 to 2020 in adults ≥ 45 years of age per 100000 population. These AAMRs were stratified by gender, ethnicity, and demographics and analyzed using Joinpoint regression to determine annual percent changes (APCs) and assess trend changes.

RESULTS

Between 1999 and 2020, a total of 114044 diverticular disease-related deaths were reported among adults ≥ 45 years of age. Our analysis reports progressive decline in mortality with AAMR decreasing from 6.7 in 1999 to 6.1 in 2003 [APC: -2.60; 95% confidence interval (CI): -3.79 to -0.33], after which it further declined to 3.6 in 2013 (APC: -5.16; 95%CI: -7.26 to -4.74), with a minimal decrease to 3.5 in 2020 (APC: -0.65; 95%CI: -1.87 to 1.51). Women had a higher AAMR (4.8) than men (3.8) throughout the study period. The racial analysis reported the highest overall AAMR in non-Hispanic (NH) Whites (4.7), followed by NH Black or African American (3.9), Hispanic or Latino (3.1), and Asian or Pacific Islander (1.5), with unreliable data for the American Indian or Alaska Native population. States in the top 90^th percentile, such as Wyoming and Vermont, had approximately double the AAMRs compared to states in the bottom 10^th percentile. The mortality rate also exhibited regional disparities, with an overall AAMR higher in the Midwest and West regions (4.7) compared to the Northeast and South regions (4.2), and higher in nonmetropolitan areas (5.4) compared to metropolitan areas (4.2).

CONCLUSION

Although the annual mortality of diverticular disease has decreased since 1999, there are certain demographic and regional disparities, with mortality rates higher in women, NH White and NH Black adults, Western regions, and nonmetropolitan areas. Further research is needed to identify factors responsible for these disparities and plan appropriate interventions.

Key Words: Mortality; Diverticular disease; Demographic trends; Regional trends; Analysis

Core Tip: There is limited comprehensive data on mortality rates due to diverticular disease. This study aims to investigate the mortality trends of diverticular disease over a two-decade period through demographic and regional stratification. Overall mortality has decreased over two decades; however, females and non-Hispanic whites have higher mortality rates. The study also identifies states and regions showing higher mortality rates. The study suggests that further research is necessary to identify the factors contributing to demographic and regional disparities in mortality, thereby enhancing public health measures for vulnerable populations.

INTRODUCTION

Gastrointestinal disease is one of the major causes of morbidity and mortality in the United States[1]. Among gastrointestinal diseases, diverticular disease of the intestine is one of the most common gastrointestinal conditions encountered by emergency physicians, surgeons, and gastroenterologists. It is one of the top five most common gastrointestinal conditions in the Western world[2]. In 2012, diverticular disease was deemed responsible for approximately 0.3 million in-hospital admissions in the United States, at a cost of $2.2 billion[3]. Diverticulosis is one of the most typical findings encountered at colonoscopy. The incidence of diverticular disease increases with age and with other risk factors such as constipation, increased intake of meat, and lack of dietary fiber[4]. Diverticular disease can remain asymptomatic; however, in 20% of cases, it can lead to acute diverticulitis, an acute inflammation of the bowel diverticula[5]. A third of patients admitted with acute diverticulitis have associated complications, including obstruction, perforation, abscess, and peritonitis, which increases inpatient mortality[6]. Considering the prevalence of diverticular disease and its economic burden on the United States healthcare system, this study aims to examine the mortality trends of diverticular disease according to demographics and regional differences in adults aged 45 and above in the United States. This type of study has not been undertaken before; thus, it would help identify groups and regions with increasing diverticular disease-related mortality, allowing for the planning of appropriate interventions and the effective utilization of healthcare resources. Previous studies have described the prevalence of diverticular disease based on hospitalization rates and colonoscopy data. They have also stratified mortality rates due to diverticular disease by sex. This study aims to comprehensively stratify diverticular disease mortality by sex, race, and region over a two-decade period, a task that has not been previously undertaken or reported.

MATERIALS AND METHODS

Population and study setting

This investigation utilized the CDC WONDER database to extract mortality data from the death certificates. This data was examined from 1999 to 2020 to identify diverticular disease of intestine-related mortality in adults aged 45 years or older, using the International Statistical Classification of Diseases and Related Health Problems-10th Revision (ICD-10) codes, K57.0 to K57.9. In other studies, these same ICD codes have been used to identify diverticular disease of the intestine[7,8]. The Multiple Cause-of-Death Public Use Registry was used to select only those death certificates in which diverticular disease was identified as the underlying or the contributing cause of death. This data set includes mortality data from 50 states and the District of Columbia. The adults in this study were defined as those who were 45 years or older at the time of death, as the incidence of diverticular disease rises above this age; however, the incidence is also increasing in young adults (18-44 years)[9]. The study did not require Institutional Review Board approval, as it contains de-identified patient data from the CDC database. This aligns with the institutional guidelines of CDC WONDER for the use of this data. The study adheres to the STROBE guidelines for reporting observational data.

Data abstraction

Mortality data reported in this study were abstracted for demographics, geographical regions, states, urban-rural classification, and place of death. All data abstraction included adults aged 45 years or older at the time of death. The demographics included stratification of deaths in terms of sex and race/ethnicity. The geographical regions were divided into Northeast, Midwest, South, and West, following the United States Census Bureau Classification, and have been used in similar studies[10]. The study reports diverticular disease-related deaths in the 50 states and the District of Columbia. The urban-rural classification was done by comparing deaths in metropolitan and non-metropolitan areas. This classification was based on the National Center for Health Statistics, which assessed population by urban [large metropolitan area (a population of 1 million or more), medium/small metropolitan area (population ranging from 50000-999999)] and rural (population less than 50000) counties by the 2013 United States census classification[11]. The mortality data compared deaths through their location, including those at medical facilities (outpatient, inpatient, emergency room, death on arrival, and unknown status), homes, nursing homes/Long-term care facilities, and hospices. The racial mortality data were classified into Non-Hispanic (NH) White, NH Black or African American, NH American Indian or Alaskan Native, NH Asian or Pacific Islander, and Hispanic or Latino. Similar data abstraction methods have been used in previous analyses of CDC WONDER[12].

Statistical analysis

The study aimed to examine diverticular disease-related mortality from 1999 to 2020 to identify national trends. This was done by extracting crude mortality rates and age-adjusted mortality rates (AAMRs) with 95% confidence intervals (CIs) per 100000 United States population from the death certificate data retrieved from the CDC database, stratified by sex, race, age, geographical regions, states, urban-rural status, and location of death. This data also reported the total number of deaths and the population in the specified year. We obtained the crude mortality rates by dividing the total number of deaths by the United States population in that particular year. The AAMRs, on the other hand, were obtained by dividing the total number of deaths by the standard United States population in the year 2000 to obtain standardized rates[13]. These standardized age-adjusted rates were then analyzed using the Joinpoint Regression Program (Version 5.0.2, National Cancer Institute) to generate Annual Percent Changes (APCs) with 95%CIs in AAMRs[14,15]. This program employed long-linear regression analysis to identify changes in AAMRs from 1999 to 2020 and generate APCs, which helped identify trends in diverticular disease mortality from 1999 to 2020. Depending on the mortality slope showing a significant difference from zero using 2-tailed t-testing, the APCs were accordingly classified as increasing or decreasing. These analyses yielded a P value that was considered statistically significant when less than 0.05.

RESULTS

Overall, 114044 deaths were reported to be linked to diverticular disease of the intestine in adults who were 45 years or older, according to the death certificates retrieved from CDC WONDER from 1999 to 2020 (Supplementary Table 1). An analysis of deaths through their location reported 110914 deaths; 65.9% of these were reported at medical facilities, 16.8% at nursing homes/Long-term care facilities, 4% at hospices, and 13.1% at homes (Supplementary Table 2).

Diverticular disease-related yearly patterns in AAMR

The AAMRs for diverticular disease of the intestine in 1999 was 6.7 (95%CI: 6.5-6.9). The AAMR dropped to 3.5 (95%CI: 3.4-3.6) in 2020. A joinpoint regression analysis showed that from 1999 to 2003, the AAMR declined with an APC of -2.60 (95%CI: -3.79 to -0.33). The AAMR further decreased from 2003-2013, showing an APC of -5.16 (95%CI: -7.26 to -4.74), while from 2013-2020, there was a slight decrease with an APC of -0.65 (95%CI: -1.87-1.51) (Figure 1A, Supplementary Tables 3 and 4).

Figure 1 Diverticular disease of intestine-related age-adjusted mortality rates per 100000 in the United States, 1999 to 2020. A: Stratified by sex in adults; B: Stratified by race in adults; C: Stratified by state in adults; D: Stratified by census region in adults; E: Stratified by urban-rural status in adults. ^aP < 0.05. ¹Age-adjusted mortality rates not entered due to unreliable data. APC: Annual percent changes; NH: Non-Hispanic.

Diverticular disease-related yearly patterns in AAMR stratified by gender

During the longitudinal examination from 1999 to 2020, it was found that females had a higher overall AAMR of 4.8 (95%CI: 4.8-4.9) compared to males, whose overall AAMR was 3.8 (95%CI: 3.7-3.8) in the target population. The AAMR of males in 1999 was 5.7 (95%CI: 5.4-5.9), which decreased to 3 (95%CI: 2.9-3.2) in 2020. A trend analysis of these AAMRs showed an annual percent decrease of -1.29 (95%CI: -2.94-1.16) from 1999-2002 and a further steady annual decline of -5.29 (95%CI: -5.94 to -4.94) from 2002 to 2013. From 2013 to 2020, the AAMR in males remained relatively stable, with an APC of -0.44 (95%CI: -1.47-0.94). In the case of females, the AAMR was 7.3 (95%CI: 7.1-7.5) in 1999. This steadily declined to an AMMR of 6.7 (95%CI: 6.5-6.9) with an annual percent decrease of -2.54 (95%CI: -3.91-0.34). The trend analysis showed further reduction in female AAMR from 2003 to 2011 with an APC of -5.26 (95%CI: -8.03 to -4.19) and from 2011 to 2018 with an APC of -2.24 (95%CI: -6.74 to -0.41). The AAMR in females showed a significant escalation from 3.6 (95%CI: 3.5-3.7) in 2018 to 3.9 (95%CI: 3.8-4) in 2020, with an APC of 3.81 (95%CI: -1.97-7.62) (Figure 1A, Supplementary Tables 3 and 4).

Diverticular disease-related yearly patterns in AAMR stratified by race/ethnicity

The mortality data stratified by race revealed that diverticular disease-related AAMR was highest in the NH White population [4.7 (95%CI: 4.6-4.7)], followed by NH Black or African American community [3.9 (95%CI: 3.9-4)], Hispanic or Latino population [3.1 (95%CI: 3.1-3.2)], and NH Asian or Pacific Islander [1.5 (95%CI: 1.4-1.6)]. The AAMRs for the NH American Indian or Alaska Native population were unreliable and not included. This is because the number of mortalities in these groups for the given age was too low for the CDC WONDER to calculate AAMRs accurately. The AAMR of the NH White population showed a consistent decline from 1999 to 2003 with an APC of -2.66 (95%CI: -3.81 to -0.47) and from 2003 to 2013 with an APC of -4.94 (95%CI: -7.10 to -4.53). It remained relatively stable from 2013 to 2020 with an APC of -0.34 (95%CI: -1.48-1.56). The AAMR of the NH African American population diminished throughout the years, decreasing with an APC of -5.08 (95%CI: -7.56 to -4.42) from 1999-2014 and an APC of -0.92 (95%CI: -3.61-9.85) from 2014-2020. The AAMR of the Hispanic population showed an interesting trend, decreasing from 1999 to 2018 with an APC of -3.87 (95%CI: -4.70 to -3.28) but rising considerably from 2018 to 2020 with an APC of 11.7 (95%CI: 2.27-17.3). The AAMR of the NH Asian or Pacific Islander population showed a similar trend, lowering from 1999 to 2015 with an APC of -5.33 (95%CI: -12.3 to -3.69) and then rising with an APC of 2.07 (95%CI: -3.42-14.5) (Figure 1B, Supplementary Tables 3 and 5).

Diverticular disease-related yearly patterns in AAMR stratified by states

The study period reported different AAMRs in different states of the United States. The lowest diverticular disease-related overall AAMR was recorded as 3.1 (95%CI: 2.8 to 3.4) for Hawaii. In contrast, Vermont had the highest overall AAMR, at 8.1 (95%CI: 7.3 to 8.8). All other states had their AAMRs scattered between these two opposites. The states with AAMRs in the lowest 10^th percentile included Hawaii, Nevada, Arizona, Louisiana, Florida, Georgia, and Utah. The states with AAMRs in the top 90^th percentile included West Virginia, Nebraska, Iowa, Rhode Island, Maine, South Dakota, Wyoming, and Vermont (Figure 1C, Supplementary Table 6).

Diverticular disease-related yearly patterns in AAMR stratified by census regions

The mortality data stratified by census regions showed that from 1999 to 2020, the Midwest and West had a higher overall AAMR of 4.7 (95%CI: 4.7-4.8) compared to the Northeast and South regions’ overall AAMR of 4.2 (95%CI: 4.1-4.3). The AAMR of the Midwest showed considerable reduction from 1999 to 2006 and 2006 to 2014, with an annual percent decrease of -3.04 (95%CI: -4.12 to -0.79) and -6.28 (95%CI: -8.65 to -5.46), respectively. It remained relatively constant from 2014 to 2020 with an APC of 0.14 (95%CI: -1.29-2.31). The AAMR of the West region had a consistent annual percent decline of -4.72 (95%CI: -5.65 to -4.06) from 1999 to 2013, after which it remained reasonably stable till 2020 with an APC of -0.06 (95%CI: -1.79-3.90). The Northeast region also showed an annual percent decline of -4.64 (95%CI: -10.1 to -3.39) and -2.44 (95%CI, -3.22-1.21) from 1999 to 2008 and 2008 to 2020, respectively. The AAMR of the South lessened by an APC of -1.79 (95%CI: -3.49-1.53) from 1999 to 2003. It then reduced further by an annual percent decline of -6.24 (95%CI: -10.2 to -5.34) from 2003 to 2011 and -1.21 (95%CI: -2.52 to 1.27) till 2020 (Figure 1D, Supplementary Tables 3 and 7).

Diverticular disease-related yearly patterns in AAMR stratified by urbanization

This longitudinal study revealed that nonmetropolitan areas had a higher overall AAMR of 5.4 (95%CI: 5.3 to 5.4) compared to the metropolitan overall AAMR of 4.2 (95%CI: 4.2 to 4.3) due to the diverticular disease of intestine from 1999 to 2020. The AAMR in nonmetropolitan areas had a considerable annual percent increase of 2.55 (95%CI: -4.13 to 2.10) from 1999 to 2004. It declined by a yearly percentage of -4.97 (95%CI: -7.99 to -4.36) till 2015 but increased again with an APC of 0.25 (95%CI: 1.72 to 4.12) till 2020. The metropolitan areas, on the other hand, had a consistent annual percent decline of -2.58 (95%CI: -3.71 to -0.41), -5.39 (95%CI: -7.89 to -4.78), and -2.04 (95%CI: -5.52 to -0.58) from 1999-2003, 2003-2011, and 2011-2018, respectively. However, it showed a considerable annual percent increase of 4.24 (-1.21 to 7.42) from 2018 to 2020 (Figure 1E, Supplementary Tables 3 and 8).

DISCUSSION

This retrospective longitudinal study has revealed some key findings regarding mortality rates of diverticular disease in adults in the United States over 21 years that have profound public health implications. The death certificate data from the CDC WONDER database shows that the annual mortality due to diverticular disease has declined consistently and progressively from 1999 to 2013. After that, the yearly mortality has remained relatively stable, with only a minimal annual percent decrease till 2020. This decrease in annual mortality is likely attributable to more disease screening and awareness, better healthcare resources, and treatment modalities over the past two decades, as the prevalence of diverticular disease has risen, in contrast, indicated by increased hospitalization rates[16]. The mortality rates have demonstrated spikes in the terminal part of the study period in some sub-groups, including women and the Midwest and West regions. These trend changes may be explained by shifts in healthcare access, broader systemic factors, and the impact of the coronavirus disease 2019 pandemic in 2020. There has been an increased prevalence of diverticular disease in the past two decades, particularly in patients younger than 50 years of age[17,18]. This enhancement is ascribable to decreased physical activity, a rise in obesity, and reduced fiber intake[19,20].

The study shows significant sex-stratified differences in mortality, where the overall mortality due to diverticular disease is higher in women compared to men from 1999 to 2020. These findings concur with the findings of another study that reported higher mortality due to diverticulitis in females compared to males in the United States[21]. These mortality rates differ from the general mortality trends, where males generally have higher mortality due to most causes of death[22,23]. It is reported that the incidence of diverticular disease is higher in men before 50 years of age, but higher in women above 50 years of age[24]. Another study, however, reports that females have reduced odds of diverticulosis at any age compared to males, based on colonoscopy data gathered from 2000 to 2012[25]. Nonetheless, our study demonstrates that after a consistent decrease in the female mortality rate from 1999 to 2018, it increased considerably from 2018 to 2020, requiring investigation for probable causes. The mortality rate in males shows a progressive downward trend.

The study also demonstrates significant racial differences in diverticular disease-related mortality. The mortality rate was highest in the NH White community and lowest in the NH Asian or Pacific Islander community. These mortality rates align with the racial differences in the prevalence of diverticulosis observed in colonoscopy data[25]. The mortality rates of the NH Asian or Pacific Islander population and Hispanic or Latino population have demonstrated a considerable increase close to 2020 after years of consistent decrease. In light of these mortality rates, a culturally tailored approach should be adopted to plan interventions to target ethnically vulnerable groups.

The analysis also highlights remarkable differences in diverticular disease mortality across different states, where states such as West Virginia, Nebraska, Iowa, Rhode Island, Maine, South Dakota, Wyoming, and Vermont had almost double the mortality rates compared to states like Hawaii, Nevada, Arizona, Louisiana, Florida, Georgia, and Utah. This difference is likely attributable to multifactorial causes and requires policy changes in the highly affected states to lower mortality.

A noteworthy point this analysis disclosed was the higher mortality rates in nonmetropolitan areas compared to metropolitan areas over 21 years of study. Although the mortality trends show a downward progression in both regions, the mortality rates fairly escalated in the urban areas from 2018 to 2020, which is of concern. The increased burden of mortality in nonmetropolitan areas is likely due to low socioeconomic status in rural areas and limited access to primary care physicians and specialists. A study reveals that from 2002 to 2015, the number of primary care physicians in rural areas declined twice as much as in urban areas, which likely explains these disparities[26].

A geographical analysis demonstrated that the Midwest and West had higher mortality due to diverticular disease than the Northeast and South regions from 1999 to 2020. A study investigating diverticulitis admissions from 1998 to 2005 reported the highest number of admissions in the Northeast region due to diverticulitis[16]. Our investigation, however, reveals that mortality due to diverticulitis is higher in the Midwest and Western regions. These regional disparities are partly attributable to differences in lifestyles, dietary habits, quality of healthcare, and Medicaid regulations. Extensive longitudinal studies are necessary to identify the primary factors responsible for these disparities and to plan interventions accordingly.

While our study reports some critical aspects of diverticular disease mortality, it has certain limitations. The data extracted from the CDC WONDER was based on ICD-10 codes on death certificates. There is an inherent risk of omission of some deaths where diverticular disease was a cause of death. The data also does not provide socioeconomic determinants of patients, the treatments received, investigative findings (such as colonoscopy results), dietary and behavioral factors, and a family history of diverticulosis, all of which would help better understand the epidemiology and prevalence of diverticular disease.

CONCLUSION

Although the prevalence of diverticular disease is increasing in the United States, our study reports a declining trend in the AAMRs of diverticular disease in adults from 1999 to 2020. The higher AAMRs were observed in females, NH Whites, NH Blacks, and in the states of West Virginia, Nebraska, Iowa, Rhode Island, Maine, South Dakota, Wyoming, and Vermont, as well as in the Midwest and West regions, and nonmetropolitan areas. Further research is necessary to identify the contributing factors to mortality in vulnerable populations and to intensify efforts for prevention and treatment.