Combining risk estimates from observational studies with different exposure cutpoints: a meta-analysis on body mass index and diabetes type 2

Studies on a dose-response relation often report separate relative risks for several risk classes compared with a referent class. When performing a meta-analysis of such studies, one has to convert these relative risks into an overall relative risk for a continuous effect. Apart from taking the dependence between separate relative risks into account, this implies assigning an exposure level to each risk factor class and allowing for the nonlinearity of the dose-response relation. The authors describe a relatively simple method solving these problems. As an illustration, they applied this method in a meta-analysis of the association between body mass index and diabetes type 2, restricted to results of follow-up studies (n=31). Results were compared with a more ad hoc method of assigning exposure levels and with a method in which the nonlinearity of the dose-response method was not taken into account. Differences with the ad hoc method were larger in studies with fewer categories. Not incorporating the nonlinearity of the dose response leads to an overestimation of the pooled relative risk, but this bias is relatively small.     

国内公共卫生类期刊文献抽样设计质量调查表信效度评价

  目的  了解上海市嘉定区社区居民常见慢性病多病共患现状及其影响因素, 为社区居民常见慢性病多重患病的综合防控提供参考依据。  方法  于2019年7 — 9月采用多阶段随机整群抽样方法在上海市嘉定区抽取3 个街镇12个居委会/村10053名20～75岁常住户籍居民进行问卷调查和体格检查。  结果  上海市嘉定区10053名社区居民中, 患多种慢性病者4920例,慢性病多病共患率为48.94 %;在4920例多病共患慢性病者中,患2种慢性病者1 988例（40.41 %）,患3种慢性病者1314例（26.71 %）,患 ≥ 4种慢性病者1618例（32.89 %）。多因素非条件logistic回归分析结果显示,男性、年龄 ≥ 30岁、未体育锻炼和睡眠质量差是上海市嘉定区社区居民常见慢性病多病共患的危险因素;不吸烟、睡眠质量好和不吃甜食是上海市嘉定区社区居民常见慢性病多病共患的保护因素。  结论  上海市嘉定区社区居民慢性病多病共患率较高, 性别、年龄、吸烟情况、体育锻炼情况、睡眠质量和甜食喜好是当地社区居民常见慢性病多病共患的主要影响因素。     

Body mass index and mortality: a twelve-year prospective study in Korea

The relation between body mass index (kg/m2) and noncoronary mortality is not well established. To study this relation, a population with low coronary mortality may be especially useful. We conducted a 12-year follow-up study of 235,398 Korean men 40-64 years of age. Study subjects had undergone health examinations in 1986 (baseline) and 1990. We excluded subjects with substantial weight loss during this period. There were 13,387 deaths, including 600 deaths from coronary events, between 1990 and 1998. We estimated the relation of body mass index to the risk of death after adjusting for common risk factors. There was a positive relation between body mass index and coronary mortality, but this relation was attenuated after serum total cholesterol, blood pressure, and fasting serum glucose were taken into account. A J-shaped relation with cerebrovascular mortality was also attenuated after adjustment. Even after this adjustment and exclusion of early deaths between 1990 and 1994, the relation of body mass index to all-cause (U-shaped), cancer (J-shaped), and noncancer noncoronary noncerebrovascular (inverse J-shaped) mortality remained. Both high and low body mass index were related to increased mortality among these Korean men.     

Body mass index and mortality in a middle-aged Japanese cohort

BACKGROUND: The relative risk of mortality in low and high body mass index (BMI) categories in various ethnic groups remains a controversial subject. METHODS: To examine the relationship between BMI and mortality, a population-based prospective cohort study was conducted in two areas of Gunma Prefecture, Japan, in 1993. A total of 5,554 men and 5,827 women aged 40-69 years completed a self-administered questionnaire and were followed up until the year 2000. The hazard ratios (HRs) were estimated by the Cox proportional hazards model for different BMI classes. RESULTS: During the seven year follow-up period, 329 men and 147 women died. As compared with those in the reference BMI category (22.0-24.9 kg/m(2)), men and women in the lowest BMI category (<18.5 kg/m(2)) had a HR (95% confidence interval [CI]) of death from all-causes of 2.66 (1.59-4.46) and 3.14 (1.38-7.13), respectively, and women in the highest BMI category (28.0+ kg/m(2)) had a HR of death of 3.25 (1.48-7.15), after adjusting for all possible confounding factors including smoking and after excluding deaths occurring during the first three years of follow-up. CONCLUSION: In this prospective study of a Japanese cohort consisting of subjects ranging in age from 40 to 69 years, the curve depicting the relationship between BMI and all-cause mortality was L-shaped in men and U-shaped in women.     

Body mass index and biliary tract disease: A systematic review and meta-analysis of prospective studies

ObjectiveTo evaluate the association between body mass index (BMI, kg/m²) and incidence of biliary tract disease.MethodsWe performed a systematic review and a meta-analysis of prospective studies by searching the database of PubMed and EMBASE published up to December 31, 2013. Outcome of interest was disease of biliary tract system (gallbladder, extrahepatic bile duct and Ampullar of Vater). We used a random-effects model to combine the study-specific relative risks (RRs) and 95% confidence intervals (95% CIs) from 22 prospective studies. We examined whether BMI was associated with a higher risk of biliary tract disease in a combined analysis.ResultsThe positive association was stronger for non-cancer biliary tract disease than biliary tract cancer; combined RRs (95% CIs) comparing the top with bottom categories were 1.40 (1.15–1.65) for biliary tract cancer and 2.75 (2.35–3.15) for non-cancer biliary tract disease (P for difference < 0.001). For non-cancer biliary tract disease, combined RRs (95% CIs) comparing the top with bottom categories were 3.21 (2.48–3.93) for women and 2.01 (1.66–2.37) for men (P for difference = 0.04).ConclusionObesity is associated with higher risks of biliary tract cancer and, to a greater extent, non-cancer biliary tract disease.     

Primary care attributes and mortality: a national person-level study

PURPOSE

Research demonstrates an association between the geographic concentration of primary care clinicians and mortality in the area, but there is limited evidence of a mortality benefit of primary care at the individual patient level. We examined whether patient-reported access to selected primary care attributes, including some emphasized in the medical home literature, is associated with lower individual mortality risk.

METHODS

We analyzed data from 2000–2005 Medical Expenditure Panel Survey respondents aged 18 to 90 years (N = 52,241), linked to the National Death Index through 2006. A score was constructed from 5 yes/no items assessing whether the respondent’s usual source of care had 3 attributes: comprehensiveness, patient-centeredness, and enhanced access. Scores ranged from 0 to 1 (higher scores = more attributes). We examined the association between the primary care attributes score and mortality during up to 6 years of follow-up using Cox survival analysis, adjusted for social, demographic, and health-related characteristics.

RESULTS

Racial/ethnic minorities, poorer and less educated persons, individuals without private insurance, healthier persons, and residents of regions other than the Northeast reported less access to primary care attributes than others. The primary care attributes score was inversely associated with mortality (adjusted hazard ratio = 0.79; 95% confidence interval, 0.64–0.98; P = .03); supplementary analyses showed mortality decreased linearly with increasing score.

CONCLUSIONS

Greater reported patient access to selected primary care attributes was associated with lower mortality. The findings support the current interest in ensuring that patients have access to a medical home encompassing these attributes.     

Body mass index and mortality in middle-aged Korean women

PURPOSE: We sought to evaluate the association between body mass index (BMI) and mortality in Korean women and to determine whether the association differs depending on menopausal status. METHODS: A total of 338,320 Korean women ages 40 to 64 years categorized into seven groups by BMI level were prospectively followed for mortality from approximately 1994 to 2004. RESULTS: Multivariable-adjusted analysis using Cox proportional hazards model showed a U-shaped association between BMI and all-cause deaths, with the lowest risk at BMI between approximately 25 and 26.9 kg/m2, even after excluding earlier deaths, which did not change when we did a stratified analysis according to menopausal status. A U-shaped association was observed between BMI and cancer death, and the risk associated with low BMI decreased significantly after excluding earlier cancer deaths. There was a J-shaped association between BMI and coronary heart disease (CHD) with a significantly increased risk at greater BMI (>26 kg/m2). Additional adjustment for possible biological effects of obesity (i.e., serum total cholesterol, glucose, and systolic blood pressure) changed the U-shaped association between BMI and all-causes mortality into an inverse shape and substantially reduced the size of risk for CHD death associated with high BMI level. In stratified analysis, the association between BMI and CHD was positive linear in women at premenopausal status, whereas it was U-shaped in women at postmenopausal status. CONCLUSIONS: Obesity was associated with an increased risk of mortality in both premenopausal and postmenopausal Korean women, indicating that preventive strategies to control obesity are important even in population with a relatively low mean BMI level.     

Body mass index and mortality among US male physicians

PURPOSE: To assess the relationship between body mass index and mortality in a population homogeneous in educational attainment and socioeconomic status. METHODS: We analyzed the association between body mass index (BMI) and both all-cause and cause-specific mortality among 85,078 men aged 40 to 84 years from the Physicians' Health Study enrollment cohort. RESULTS: During 5 years of follow-up, we documented 2856 deaths (including 1212 due to cardiovascular diseases and 891 due to cancer). In age-adjusted analyses, we observed a U-shaped relation between BMI and all-cause mortality; among men who never smoked a linear relation was observed with no increase in mortality among leaner men (P for trend, <0.001). Among never smokers, in multivariate analyses adjusted for age, alcohol intake, and physical activity, the relative risks of all-cause mortality increased in a stepwise fashion with increasing BMI. Excluding the first 2 years of follow-up further strengthened the association (multivariate relative risks, from BMI<20 to > or = 30 kg/m2, were 0.93, 1.00, 1.00, 1.16, 1.45, and 1.71 [P for trend, <0.001]). In all age strata (40-54, 55-69, and 70-84 years), never smokers with BMIs of 30 or greater had approximately a 70% increased risk of death compared with the referent group (BMI 22.5-24.9). Higher levels of BMI were also strongly related to increased risk of cardiovascular mortality, regardless of physical activity level (P for trend, <0.01). CONCLUSIONS: All-cause and cardiovascular mortality was directly related to BMI among middle-aged and elderly men. Advancing age did not attenuate the increased risk of death associated with obesity. Lean men (BMI<20) did not have excess mortality, regardless of age.     

Body mass index in young adulthood and cancer mortality: a retrospective cohort study

STUDY OBJECTIVE: To examine the relation between body mass index (BMI) in young adulthood and subsequent mortality from cancer. DESIGN: Cohort study. SETTING: University of Glasgow student health service. Weight and height were measured by a physician, and used to calculate BMI. PARTICIPANTS: 8335 men and 2340 women who attended the student health service while at university between 1948 and 1968, and who were followed up with the NHS central register. MAIN RESULTS: The main outcome measure was cancer mortality. Three hundred and thirty nine men and 82 women died of cancer during the follow up (mean 41 years). BMI was associated with mortality from all cancers in men and women, although it did not reach conventional statistical significance. The adjusted hazard ratio (HR) (95% CI) per 5 kg/m(2), was 1.22 (0.97 to 1.53) in men and 1.43 (0.95 to 2.16) in women. Two hundred men and 61 women died from cancers not related to smoking. The adjusted HR for mortality from these were 1.36 (1.02 to 1.82) and 1.80 (1.13 to 2.86) respectively. These results are adjusted for height, number of siblings, pulse rate, year of birth, age, smoking, birth order, number of siblings, and age at menarche in women. Site specific analyses, comparing the highest with the lowest quartile of the BMI distribution found increased risks of prostate cancer (n=28) and breast cancer among heavier subjects. No association between BMI and colorectal cancer was found. CONCLUSIONS: BMI in adolescence has lasting implications for risk of cancer mortality in later life. Future research will include measures of BMI throughout the lifecourse, to determine the period of greatest risk of obesity, in terms of cancer mortality.     

Body mass index and colon cancer mortality in a large prospective study

Obesity has been reported to increase the risk of colon cancer, especially in men. The authors examined this relation in the American Cancer Society's Cancer Prevention Study II, a nationwide mortality study of US adults. After 12 years of follow-up, 1,616 deaths from colon cancer in women and 1,792 in men were observed among 496,239 women and 379,167 men who were cancer free at enrollment in 1982. The authors used Cox proportional hazards analyses to control for effects of age, race, education, smoking, exercise, alcohol, parental history of colon cancer, fat intake, vegetable and grain intake, aspirin use and, in women, estrogen replacement therapy. In men, death rates from colon cancer increased across the entire range of body mass index (BMI). The rate ratio was highest for men with BMI > or =32.5 (rate ratio (RR) = 1.90, 95% confidence interval (CI): 1.46, 2.47) compared with men with BMI between 22.00 and 23.49. In women, a weaker association was seen in the three BMI categories of 27.5-29.9 (RR = 1.26, 95% CI: 1.03, 1.53), 30.0-32.4 (RR = 1.37, 95% CI: 1.09, 1.72), and > or =32.5 (RR = 1.23, 95% CI: 0.96, 1.59). These prospective data support the hypothesis that obesity increases the risk of colon cancer death and that the relation is stronger and more linear in men than in women.     

Body mass index and physical activity and the risk of diverticular disease: a systematic review and meta-analysis of prospective studies

Purpose

We conducted a systematic review and meta-analysis of prospective studies of the association between body mass index (BMI) and physical activity and diverticular disease risk.

Methods

PubMed and Embase databases were searched up to February 7, 2017. Summary relative risks and 95% confidence intervals (95% CIs) were calculated using a random effects model and nonlinear associations were modeled using fractional polynomial models.

Results

Six cohort studies of BMI and diverticular disease risk (28,915 cases, 1,636,777 participants) and five cohort studies of physical activity and diverticular disease risk (2080 cases, 147,869 participants) were included. The summary relative risk (RR) of incident diverticular disease for a 5 unit BMI increment was 1.28 (95% CI: 1.18–1.40, I ²?=?77%, n?=?6) for diverticular disease, 1.31 (95% CI: 1.09–1.56, I ²?=?74%, n?=?2) for diverticulitis, and 1.20 (95% CI: 1.04–1.40, I ²?=?56%, n?=?3) for diverticular disease complications. There was no evidence of a nonlinear association between BMI and diverticular disease risk (p _nonlinearity?=?0.22), and risk increased even within the normal weight range. Compared to a BMI of 20, the summary RR for a BMI of 22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0 was 1.15 (1.07–1.23), 1.31 (1.17–1.47), 1.50 (1.31–1.71), 1.71 (1.52–1.94), 1.96 (1.77–2.18), 2.26 (2.00–2.54), 2.60 (2.11–3.21), and 3.01 (2.06–4.39), respectively. The summary RR was 0.76 (95% CI: 0.63–0.93, I ²?=?54%, n?=?5) for high vs. low physical activity and 0.74 (95% CI: 0.57–0.97, I ²?=?39.5%, p _{heterogeneity}?=?0.20, n = 2) for high vs. low vigorous physical activity.

Conclusions

These results suggest that even moderate increases in BMI may increase the risk of diverticular disease as well as diverticular disease complications and that a higher level of physical activity may reduce the risk.

     

Body mass index and mortality in South Korean men resulting from cardiovascular disease: a Kangwha cohort study

PURPOSE: The purpose of this study was to examine the association of body mass index (BMI) with death caused by total cardiovascular disease in a long-term follow-up study. METHODS: We followed a total of 2608 men who were 55 years or older in 1985 from March 1985 through December 2001 to investigate their mortality. The hazard ratios of mortality as the result of cardiovascular disease by BMI level were estimated with the Cox proportional hazards model, adjusting for relevant covariates. RESULTS: For the group with a BMI >/= 27 kg/m(2) compared with the reference group (BMI, 21.0-22.9), the adjusted hazard ratio of death resulting from total cardiovascular disease was 2.4 (95% confidence interval [CI], 1.5-3.9) and that of death resulting from cerebrovascular disease was 3.6 (95% CI, 2.0-6.3). Observing nonsmoking subjects only, the BMI <18.5 kg/m(2) group had a 4.6 times (95% CI, 1.8-11.8) greater risk of death attributed to total cardiovascular disease than the reference group and a 4.7 times (95% CI, 1.4-16.2) greater risk of death from cerebrovascular disease. CONCLUSION: This study defined that BMI is related to Korean male deaths caused by total cardiovascular disease. The risk of death attributed to total cardiovascular disease and cerebrovascular disease was significantly increased in the group, with a BMI >/=27 kg/m(2). In our study, in the case of nonsmokers, low BMI was shown to be related to deaths from cardiovascular disease. Such result is different from those of previous studies.     

Body mass index and mortality from all causes and major causes in Japanese: results of a pooled analysis of 7 large-scale cohort studies

Background

We pooled data from 7 ongoing cohorts in Japan involving 353 422 adults (162 092 men and 191 330 women) to quantify the effect of body mass index (BMI) on total and cause-specific (cancer, heart disease, and cerebrovascular disease) mortality and identify optimal BMI ranges for middle-aged and elderly Japanese.

Methods

During a mean follow-up of 12.5 years, 41 260 deaths occurred. The Cox proportional hazards model was used to estimate hazard ratios (HRs) for each BMI category, after controlling for age, area of residence, smoking, drinking, history of hypertension, diabetes, and physical activity in each study. A random-effects model was used to obtain summary measures.

Results

A reverse-J pattern was seen for all-cause and cancer mortality (elevated risk only for high BMI in women) and a U- or J-shaped association was seen for heart disease and cerebrovascular disease mortality. For total mortality, as compared with a BMI of 23 to 25, the HR was 1.78 for 14 to 19, 1.27 for 19 to 21, 1.11 for 21 to 23, and 1.36 for 30 to 40 in men, and 1.61 for 14 to 19, 1.17 for 19 to 21, 1.08 for 27 to 30, and 1.37 for 30 to 40 in women. High BMI (≥27) accounted for 0.9% and 1.5% of total mortality in men and women, respectively.

Conclusions

The lowest risk of total mortality and mortality from major causes of disease was observed for a BMI of 21 to 27 kg/m² in middle-aged and elderly Japanese.Key words: body mass index, mortality, cancer, heart disease, cerebrovascular disease     

Body mass index and the diagnosis of endometriosis: Findings from a national data linkage cohort study

BackgroundWomen with lower body mass index (BMI) have a higher risk of surgically confirmed endometriosis but this finding runs counterintuitive to the oestrogen-dependent theory for the disease. Increasingly, endometriosis is diagnosed via non-surgical methods. We examined BMI at age 18–23 years, and changes in BMI, and the risk of endometriosis according to the diagnostic method.MethodsWe analysed data from 11 794 young women, born in 1989–95, who completed six surveys as part of an Australian, longitudinal cohort study between 2013 and 2018. Women’s survey responses were linked to administrative health records to identify endometriosis. Cox proportional hazards models modelled associations between BMI at age 18–23 years, and changes in BMI, and endometriosis. Analyses were stratified by the diagnostic method of endometriosis: clinically confirmed endometriosis (based on hospital discharge diagnosis) versus clinically suspected endometriosis (women’s reports of physician-diagnosed endometriosis).ResultsThere were 223 cases of clinically confirmed endometriosis and 396 cases of clinically suspected endometriosis. Women who gained weight after age 18–23 had lower risk of clinically confirmed endometriosis than women without endometriosis whose weight remained stable (HR = 0.64, 95% CI = 0.47–0.88). Women who were overweight (HR = 1.29, 95% CI = 1.01–1.66) at age 18–23 had higher risk of clinically suspected endometriosis than women of normal weight without endometriosis.ConclusionsThe risk of clinically confirmed endometriosis was lower among women who gained weight compared to women with stable weight. The risk of clinically suspected endometriosis was higher among women who were overweight compared to normal weight.     

Body mass index and mortality: results of a cohort of 184,697 adults in Austria

There is still a debate about the role of body mass index (BMI) as a risk factor for all-cause mortality. Most investigations with large sample sizes focused on populations from the United States, studies from Central-European cohorts are not available. We investigated the association between BMI and all-cause mortality and cause-specific mortality within a cohort in Austria. Design of this article is “Cohort study”. The Subjects used were 184,697 men and women (mean age 41.7 ± 15.4 years). Weight and height were measured. Cox proportional hazards models were used to estimate hazard ratios (HR). During a median follow-up of 15.1 years 15,557 deaths (6,077 from cardiovascular disease, 4,443 from cancer and 606 from respiratory disease) were seen. A U-shaped association between BMI and all-cause mortality was observed in men and women. Compared with the reference category (BMI 22.5–24.9 kg/m2) high risks were found both in the highest category of BMI (≥35 kg/m²) with HR of 2.13 (95% CI, 1.82–2.48) in men and 1.60 (95% CI, 1.42–1.81) in women and in the lowest category (<18.5 kg/m2) with HR of 2.57 (95% CI, 2.17–3.05) in men and 1.40 (95% CI, 1.21–1.62) in women. Similar patterns were seen among ever-smokers and non-smokers. Increased mortality with increasing BMI was driven by cardiovascular diseases and to a lesser extent by cancers. Respiratory diseases contributed to mortality in the lowest BMI category independently from smoking status. Underweight and obesity were both associated with higher all-cause mortality in men and women. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.