Abstract
Background: Overweight and obese persons are at risk of a number of medical conditions which can lead to further morbidity and mortality. The primary objective of this study is to provide an estimate of the incidence of each co-morbidity related to obesity and overweight using a meta-analysis. Methods: A literature search for the twenty co-morbidities identified in a preliminary search was conducted in Medline and Embase (Jan 2007). Studies meeting the inclusion criteria (prospective cohort studies of sufficient size reporting risk estimate based on the incidence of disease) were extracted. Study-specific unadjusted relative risks (RRs) on the log scale comparing overweight with normal and obese with normal were weighted by the inverse of their corresponding variances to obtain a pooled RR with 95% confidence intervals (CI). Results: A total of 89 relevant studies were identified. The review found evidence for 18 co-morbidities which met the inclusion criteria. The meta-analysis determined statistically significant associations for overweight with the incidence of type II diabetes, all cancers except esophageal (female), pancreatic and prostate cancer, all cardiovascular diseases (except congestive heart failure), asthma, gallbladder disease, osteoarthritis and chronic back pain. We noted the strongest association between overweight defined by body mass index (BMI) and the incidence of type II diabetes in females (RR = 3.92 (95% CI: 3.10–4.97)). Statistically significant associations with obesity were found with the incidence of type II diabetes, all cancers except esophageal and prostate cancer, all cardiovascular diseases, asthma, gallbladder disease, osteoarthritis and chronic back pain. Obesity defined by BMI was also most strongly associated with the incidence of type II diabetes in females (12.41 (9.03–17.06)). Conclusion: Both overweight and obesity are associated with the incidence of multiple co-morbidities including type II diabetes, cancer and cardiovascular diseases. Maintenance of a healthy weight could be important in the prevention of the large disease burden in the future. Further studies are needed to explore the biological mechanisms that link overweight and obesity with these co-morbidities.
Generated Summary
This meta-analysis, a systematic review, aimed to estimate the incidence of co-morbidities related to obesity and overweight. The study analyzed prospective cohort studies to determine the associations between these conditions and the incidence of various diseases. The methodology involved a literature search for twenty co-morbidities, followed by extraction of data from relevant studies. Study-specific unadjusted relative risks (RRs) were calculated and pooled using the random-effects model. The primary objective was to provide an estimate of the incidence of each co-morbidity linked to obesity and overweight, leveraging a meta-analysis approach. The study focused on understanding the risk of overweight and obesity defined by BMI and WC measurements.
Key Findings & Statistics
- A total of 89 relevant and unique studies were identified.
- The review found evidence for 18 co-morbidities which met the inclusion criteria.
- The meta-analysis determined statistically significant associations for overweight with the incidence of type II diabetes, all cancers except esophageal (female), pancreatic and prostate cancer, all cardiovascular diseases (except congestive heart failure), asthma, gallbladder disease, osteoarthritis and chronic back pain.
- The strongest association between overweight defined by body mass index (BMI) and the incidence of type II diabetes in females was observed (RR = 3.92, 95% CI: 3.10–4.97).
- Statistically significant associations with obesity were found with the incidence of type II diabetes, all cancers except esophageal and prostate cancer, all cardiovascular diseases, asthma, gallbladder disease, osteoarthritis and chronic back pain.
- Obesity defined by BMI was also most strongly associated with the incidence of type II diabetes in females (12.41 (9.03–17.06)).
- For breast cancer, the pooled IRRs [95% CI] across categories of WC were 1.13 [1.01-1.07] for overweight and 1.30 [1.17–1.44] for obesity while across categories of BMI the IRRs were 1.08 [1.03–1.14] for overweight and 1.13 [1.05–1.22] for obesity.
- The pooled IRRs [95% CI] across categories of BMI for men were 2.40 [2.12-2.72] and 6.74 [5.55–8.19] in men while the corresponding IRRs in women were 3.92 [3.10-4.97] and 12.41 [9.03-17.06].
- For coronary artery disease, the RR-P [95% CI] estimates for WC were 1.41 [1.16-1.72] for overweight and 1.81 [1.45-2.25] for obesity. The corresponding results for BMI were 1.29 [1.18-1.41] and 1.72 [1.51–1.96].
Other Important Findings
- The study also presents specific findings for individual cancers, including colorectal, kidney, ovarian, pancreatic, and prostate cancers, as well as the risks of hypertension, stroke, coronary artery disease, congestive heart failure, pulmonary embolism, asthma, osteoarthritis, and gallbladder disease.
- The analysis showed that the associations between overweight and obesity were significantly associated with increased risks in these categories.
- The study found that increased WC and type II diabetes was similar but weaker in comparison with BMI.
Limitations Noted in the Document
- The study acknowledges limitations such as the exclusion of physical inactivity levels, which could confound the results.
- The authors note that the absence of physical activity data could influence findings.
- The review only identified 1 or 2 prospective cohort studies that adopted the WC measurements as the risk predictor for certain co-morbidities.
- The search strategy, while comprehensive, was limited to Medline and Embase, potentially introducing bias.
- Assessment of publication bias was not feasible for most co-morbidities due to the small number of studies.
Conclusion
This meta-analysis provides strong evidence linking overweight and obesity to the incidence of multiple co-morbidities, including type II diabetes, cancer, and cardiovascular diseases. The findings emphasize that the maintenance of a healthy weight is a crucial factor in preventing the future burden of these diseases. The study suggests the importance of examining co-morbidities within the framework of causal pathways, and it calls for further research into the specific biological mechanisms that connect overweight and obesity to the development of these conditions. The impact of the findings highlights the need for interventions focusing on weight management to mitigate the increasing healthcare expenditures. The results of the analysis highlight the need for targeted interventions aimed at weight management to reduce the burden of chronic diseases.
IFFS Team Summary
- Comprehensive review article outlines the increased risk of diseases from overweight and obesity
- Overweight and obese people suffer from
- Increased cancer of Breast, Endometrium, Ovary, Prostate, Colon/colorectal, Pancreas
- Increase Coronary Artery Disease, Congestive Heart Failure, Stroke, Pulmonary Embolism
- Increased Hypertension and Diabetes type II
- Asthma,
- Chronic Back Pain
- Gallbladder disease
- Increased cancer of Breast, Endometrium, Ovary, Prostate, Colon/colorectal, Pancreas
- Increase Coronary Artery Disease, Congestive Heart Failure, Stroke, Pulmonary Embolism
- Increased Hypertension and Diabetes type II
- Asthma,
- Chronic Back Pain
- Gallbladder disease