Obesity and gynaecological and obstetric conditions: umbrella review of the literature

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Abstract

Objective To study the strength and validity of associations between adiposity and risk of any type of obstetric or gynaecological conditions.

Design An umbrella review of meta-analyses.

Data sources PubMed, Cochrane database of systematic reviews, manual screening of references for systematic reviews or meta-analyses of observational and interventional studies evaluating the association between adiposity and risk of any obstetrical or gynaecological outcome.

Main outcomes Meta-analyses of cohort studies on associations between indices of adiposity and obstetric and gynaecological outcomes.

Data synthesis Evidence from observational studies was graded into strong, highly suggestive, suggestive, or weak based on the significance of the random effects summary estimate and the largest study in the included meta-analysis, the number of cases, heterogeneity between studies, 95% prediction intervals, small study effects, excess significance bias, and sensitivity analysis with credibility ceilings. Interventional meta-analyses were assessed separately.

Results 156 meta-analyses of observational studies were included, investigating associations between adiposity and risk of 84 obstetric or gynaecological outcomes. Of the 144 meta-analyses that included cohort studies, only 11 (8%) had strong evidence for eight outcomes: adiposity was associated with a higher risk of endometrial cancer, ovarian cancer, antenatal depression, total and emergency caesarean section, pre-eclampsia, fetal macrosomia, and low Apgar score. The summary effect estimates ranged from 1.21 (95% confidence interval 1.13 to 1.29) for an association between a 0.1 unit increase in waist to hip ratio and risk endometrial cancer up to 4.14 (3.61 to 4.75) for risk of pre-eclampsia for BMI >35 compared with <25. Only three out of these eight outcomes were also assessed in meta-analyses of trials evaluating weight loss interventions. These interventions significantly reduced the risk of caesarean section and pre-eclampsia, whereas there was no evidence of association with fetal macrosomia.

Conclusions Although the associations between adiposity and obstetric and gynaecological outcomes have been extensively studied, only a minority were considered strong and without hints of bias.

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Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants

Emily Sonestedt, Kim Overvad (2016)

Summary Background Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences of a complete set of BMI categories for adults in all countries. Methods We analysed, with use of a consistent protocol, population-based studies that had measured height and weight in adults aged 18 years and older. We applied a Bayesian hierarchical model to these data to estimate trends from 1975 to 2014 in mean BMI and in the prevalences of BMI categories (<18·5 kg/m2 [underweight], 18·5 kg/m2 to <20 kg/m2, 20 kg/m2 to <25 kg/m2, 25 kg/m2 to <30 kg/m2, 30 kg/m2 to <35 kg/m2, 35 kg/m2 to <40 kg/m2, ≥40 kg/m2 [morbid obesity]), by sex in 200 countries and territories, organised in 21 regions. We calculated the posterior probability of meeting the target of halting by 2025 the rise in obesity at its 2010 levels, if post-2000 trends continue. Findings We used 1698 population-based data sources, with more than 19·2 million adult participants (9·9 million men and 9·3 million women) in 186 of 200 countries for which estimates were made. Global age-standardised mean BMI increased from 21·7 kg/m2 (95% credible interval 21·3–22·1) in 1975 to 24·2 kg/m2 (24·0–24·4) in 2014 in men, and from 22·1 kg/m2 (21·7–22·5) in 1975 to 24·4 kg/m2 (24·2–24·6) in 2014 in women. Regional mean BMIs in 2014 for men ranged from 21·4 kg/m2 in central Africa and south Asia to 29·2 kg/m2 (28·6–29·8) in Polynesia and Micronesia; for women the range was from 21·8 kg/m2 (21·4–22·3) in south Asia to 32·2 kg/m2 (31·5–32·8) in Polynesia and Micronesia. Over these four decades, age-standardised global prevalence of underweight decreased from 13·8% (10·5–17·4) to 8·8% (7·4–10·3) in men and from 14·6% (11·6–17·9) to 9·7% (8·3–11·1) in women. South Asia had the highest prevalence of underweight in 2014, 23·4% (17·8–29·2) in men and 24·0% (18·9–29·3) in women. Age-standardised prevalence of obesity increased from 3·2% (2·4–4·1) in 1975 to 10·8% (9·7–12·0) in 2014 in men, and from 6·4% (5·1–7·8) to 14·9% (13·6–16·1) in women. 2·3% (2·0–2·7) of the world’s men and 5·0% (4·4–5·6) of women were severely obese (ie, have BMI ≥35 kg/m2). Globally, prevalence of morbid obesity was 0·64% (0·46–0·86) in men and 1·6% (1·3–1·9) in women. Interpretation If post-2000 trends continue, the probability of meeting the global obesity target is virtually zero. Rather, if these trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women. Nonetheless, underweight remains prevalent in the world’s poorest regions, especially in south Asia. Funding Wellcome Trust, Grand Challenges Canada.

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Adiposity and cancer at major anatomical sites: umbrella review of the literature

Maria Kyrgiou, Ilkka Kalliala, Georgios Markozannes … (2017)

Objective To evaluate the strength and validity of the evidence for the association between adiposity and risk of developing or dying from cancer. Design Umbrella review of systematic reviews and meta-analyses. Data sources PubMed, Embase, Cochrane Database of Systematic Reviews, and manual screening of retrieved references. Eligibility criteria Systematic reviews or meta-analyses of observational studies that evaluated the association between indices of adiposity and risk of developing or dying from cancer. Data synthesis Primary analysis focused on cohort studies exploring associations for continuous measures of adiposity. The evidence was graded into strong, highly suggestive, suggestive, or weak after applying criteria that included the statistical significance of the random effects summary estimate and of the largest study in a meta-analysis, the number of cancer cases, heterogeneity between studies, 95% prediction intervals, small study effects, excess significance bias, and sensitivity analysis with credibility ceilings. Results 204 meta-analyses investigated associations between seven indices of adiposity and developing or dying from 36 primary cancers and their subtypes. Of the 95 meta-analyses that included cohort studies and used a continuous scale to measure adiposity, only 12 (13%) associations for nine cancers were supported by strong evidence. An increase in body mass index was associated with a higher risk of developing oesophageal adenocarcinoma; colon and rectal cancer in men; biliary tract system and pancreatic cancer; endometrial cancer in premenopausal women; kidney cancer; and multiple myeloma. Weight gain and waist to hip circumference ratio were associated with higher risks of postmenopausal breast cancer in women who have never used hormone replacement therapy and endometrial cancer, respectively. The increase in the risk of developing cancer for every 5 kg/m2 increase in body mass index ranged from 9% (relative risk 1.09, 95% confidence interval 1.06 to 1.13) for rectal cancer among men to 56% (1.56, 1.34 to 1.81) for biliary tract system cancer. The risk of postmenopausal breast cancer among women who have never used HRT increased by 11% for each 5 kg of weight gain in adulthood (1.11, 1.09 to 1.13), and the risk of endometrial cancer increased by 21% for each 0.1 increase in waist to hip ratio (1.21, 1.13 to 1.29). Five additional associations were supported by strong evidence when categorical measures of adiposity were included: weight gain with colorectal cancer; body mass index with gallbladder, gastric cardia, and ovarian cancer; and multiple myeloma mortality. Conclusions Although the association of adiposity with cancer risk has been extensively studied, associations for only 11 cancers (oesophageal adenocarcinoma, multiple myeloma, and cancers of the gastric cardia, colon, rectum, biliary tract system, pancreas, breast, endometrium, ovary, and kidney) were supported by strong evidence. Other associations could be genuine, but substantial uncertainty remains. Obesity is becoming one of the biggest problems in public health; evidence on the strength of the associated risks may allow finer selection of those at higher risk of cancer, who could be targeted for personalised prevention strategies.

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Type 2 diabetes and cancer: umbrella review of meta-analyses of observational studies.

Konstantinos Tsilidis, John Kasimis, David S. Lopez … (2015)

To summarise the evidence and evaluate the validity of the associations between type 2 diabetes and the risk of developing or dying from cancer.

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Author and article information

Contributors

Ilkka Kalliala: Role: honorary clinical lecturer

Georgios Markozannes: Role: research fellow

Marc J Gunter: Role: section and group head

Evangelos Paraskevaidis: Role: professor

Hani Gabra: Role: professor

Anita Mitra: Role: clinical research fellow

Vasso Terzidou: Role: clinical senior clinical lecturer

Phillip Bennett: Role: professor

Pierre Martin-Hirsch: Role: consultant

Konstantinos K Tsilidis: Role: assistant professor

Maria Kyrgiou: Role: clinical senior lecturer

Journal

Journal ID (nlm-ta): BMJ

Journal ID (iso-abbrev): BMJ

Journal ID (publisher-id): bmj

Title: The BMJ

Publisher: BMJ Publishing Group Ltd.

ISSN (Print): 0959-8138

ISSN (Electronic): 1756-1833

Publication date Collection: 2017

Publication date (Electronic): 26 October 2017

Volume: 359

Electronic Location Identifier: j4511

Affiliations

[1 ]Department of Surgery and Cancer, IRDB, Faculty of Medicine, Imperial College, London W12 0NN, UK

[2 ]Department of Obstetrics and Gynaecology, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 2, 00029 HUS, Finland

[3 ]Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, 45110, Ioannina, Greece

[4 ]Section of Nutrition and Metabolism, International Agency for Research on Cancer (IARC), Lyon, France

[5 ]Department of Obstetrics and Gynaecology, University of Ioannina, 45500, Ioannina, Greece

[6 ]Clinical Discovery Unit, Early Clinical Development, AstraZeneca, Cambridge, UK

[7 ]West London Gynaecological Cancer Centre, Queen Charlotte’s and Chelsea-Hammersmith Hospital, Imperial Healthcare NHS Trust, London W12 0HS, UK

[8 ]Department Gynaecologic Oncology, Lancashire Teaching Hospitals, Preston PR29HT, UK

[9 ]Department of Biophysics, University of Lancaster, Lancaster, UK

[10 ]Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London W2 1PG, UK

Author notes

Correspondence to: M Kyrgiou m.kyrgiou@ 123456imperial.ac.uk

Article

Publisher ID: kali037701

DOI: 10.1136/bmj.j4511

PMC ID: 5656976

PubMed ID: 29074629

SO-VID: 279541c8-e785-4bbb-b8d4-b23fc55d813f

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This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

Obesity and gynaecological and obstetric conditions: umbrella review of the literature

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Most cited references 56

Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants

Adiposity and cancer at major anatomical sites: umbrella review of the literature

Type 2 diabetes and cancer: umbrella review of meta-analyses of observational studies.

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