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We lead multidisciplinary applied research and training to rethink the way health care is delivered in general practice and across the community.
Weight regain after behavioural weight management programmes and its impact on quality of life and cost effectiveness: Evidence synthesis and health economic analyses
Aims: We used data from a recent systematic review to investigate weight regain after behavioural weight management programmes (BWMPs, sometimes referred to as lifestyle modification programmes) and its impact on quality-of-life and cost-effectiveness. Materials and Methods: Trial registries, databases and forward-citation searching (latest search December 2019) were used to identify randomized trials of BWMPs in adults with overweight/obesity reporting outcomes at ≥12 months, and after programme end. Two independent reviewers screened records. One reviewer extracted data and a second checked them. The differences between intervention and control groups were synthesized using mixed-effect, meta-regression and time-to-event models. We examined associations between weight difference and difference in quality-of-life. Cost-effectiveness was estimated from a health sector perspective. Results: In total, 155 trials (n > 150 000) contributed to analyses. The longest follow-up was 23 years post-programme. At programme end, intervention groups achieved –2.8 kg (95%CI –3.2 to –2.4) greater weight loss than controls. Weight regain after programme end was 0.12-0.32 kg/year greater in intervention relative to control groups, with a between-group difference evident for at least 5 years. Quality-of-life increased in intervention groups relative to control at programme end and thereafter returned to control as the difference in weight between groups diminished. BWMPs with this initial weight loss and subsequent regain would be cost-effective if delivered for under £560 (£8.80-£3900) per person. Conclusions: Modest rates of weight regain, with persistent benefits for several years, should encourage health care practitioners and policymakers to offer obesity treatments that cost less than our suggested thresholds as a cost-effective intervention to improve long-term weight management. Registration: The review is registered on PROSPERO, CRD42018105744.
Opportunistic smoking cessation interventions for people accessing financial support settings: A scoping review
Aim: The aim of this work was to systematically scope the evidence on opportunistic tobacco smoking cessation interventions for people accessing financial support settings. Methods: We searched MEDLINE, Embase, PsycINFO and the Cochrane Tobacco Addiction Group specialized register to 21 March 2023. We duplicate screened 20% of titles/abstracts and all full texts. We included primary studies investigating smoking cessation interventions delivered opportunistically to people who smoked tobacco, within settings offering support for problems caused by financial hardship, for example homeless support services, social housing and food banks. Data were charted by one reviewer, checked by another and narratively synthesized. Results: We included 25 studies conducted in a range of financial support settings using qualitative (e.g. interviews and focus groups) and quantitative (e.g. randomized controlled trials, surveys and single arm intervention studies) methodologies. Evidence on the acceptability and feasibility of opportunistic smoking cessation advice was investigated among both clients and providers. Approximately 90% of service providers supported such interventions; however, lack of resources, staff training and a belief that tobacco smoking reduced illicit substance use were perceived barriers. Clients welcomed being asked about smoking and offered assistance to quit and expressed interest in interventions including the provision of nicotine replacement therapy, e-cigarettes and incentives to quit smoking. Six studies investigated the comparative effectiveness of opportunistic smoking cessation interventions on quitting success, with five comparing more to less intensive interventions, with mixed results. Conclusions: Most studies investigating opportunistic smoking cessation interventions in financial support settings have not measured their effectiveness. Where they have, settings, populations, interventions and findings have varied. There is more evidence investigating acceptability, with promising results.
Associations of BMI with COVID-19 vaccine uptake, vaccine effectiveness, and risk of severe COVID-19 outcomes after vaccination in England: a population-based cohort study
Background: A high BMI has been associated with a reduced immune response to vaccination against influenza. We aimed to investigate the association between BMI and COVID-19 vaccine uptake, vaccine effectiveness, and risk of severe COVID-19 outcomes after vaccination by using a large, representative population-based cohort from England. Methods: In this population-based cohort study, we used the QResearch database of general practice records and included patients aged 18 years or older who were registered at a practice that was part of the database in England between Dec 8, 2020 (date of the first vaccination in the UK), to Nov 17, 2021, with available data on BMI. Uptake was calculated as the proportion of people with zero, one, two, or three doses of the vaccine across BMI categories. Effectiveness was assessed through a nested matched case-control design to estimate odds ratios (OR) for severe COVID-19 outcomes (ie, admission to hospital or death) in people who had been vaccinated versus those who had not, considering vaccine dose and time periods since vaccination. Vaccine effectiveness against infection with SARS-CoV-2 was also investigated. Multivariable Cox proportional hazard models estimated the risk of severe COVID-19 outcomes associated with BMI (reference BMI 23 kg/m2) after vaccination. Findings: Among 9 171 524 participants (mean age 52 [SD 19] years; BMI 26·7 [5·6] kg/m2), 566 461 tested positive for SARS-CoV-2 during follow-up, of whom 32 808 were admitted to hospital and 14 389 died. Of the total study sample, 19·2% (1 758 689) were unvaccinated, 3·1% (287 246) had one vaccine dose, 52·6% (4 828 327) had two doses, and 25·0% (2 297 262) had three doses. In people aged 40 years and older, uptake of two or three vaccine doses was more than 80% among people with overweight or obesity, which was slightly lower in people with underweight (70–83%). Although significant heterogeneity was found across BMI groups, protection against severe COVID-19 disease (comparing people who were vaccinated vs those who were not) was high after 14 days or more from the second dose for hospital admission (underweight: OR 0·51 [95% CI 0·41–0·63]; healthy weight: 0·34 [0·32–0·36]; overweight: 0·32 [0·30–0·34]; and obesity: 0·32 [0·30–0·34]) and death (underweight: 0·60 [0·36–0·98]; healthy weight: 0·39 [0·33–0·47]; overweight: 0·30 [0·25–0·35]; and obesity: 0·26 [0·22–0·30]). In the vaccinated cohort, there were significant linear associations between BMI and COVID-19 hospitalisation and death after the first dose, and J-shaped associations after the second dose. Interpretation: Using BMI categories, there is evidence of protection against severe COVID-19 in people with overweight or obesity who have been vaccinated, which was of a similar magnitude to that of people of healthy weight. Vaccine effectiveness was slightly lower in people with underweight, in whom vaccine uptake was also the lowest for all ages. In the vaccinated cohort, there were increased risks of severe COVID-19 outcomes for people with underweight or obesity compared with the vaccinated population with a healthy weight. These results suggest the need for targeted efforts to increase uptake in people with low BMI (<18·5 kg/m2), in whom uptake is lower and vaccine effectiveness seems to be reduced. Strategies to achieve and maintain a healthy weight should be prioritised at the population level, which could help reduce the burden of COVID-19 disease. Funding: UK Research and Innovation and National Institute for Health Research Oxford Biomedical Research Centre.
Weight trajectories and access to weight management services in individuals with severe mental illness in the UK: a population-based, matched cohort study
Background: Excess weight is common in people with severe mental illness, including schizophrenia spectrum disorders, bipolar disorder, and other non-organic psychotic disorders. Rapid weight gain often follows use of antipsychotics, but long-term weight trajectories are unclear. We aimed to compare 15-year weight trajectories and assess the incidence of weight management advice and referrals among people with and without severe mental illness. Methods: In this retrospective, matched cohort study, we used the Clinical Practice Research Datalink Aurum to identify people aged 18–65 years registered at 1454 primary care practices in England (UK) between Jan 1, 1998, and Oct 31, 2020. 12 people with lived experience of severe mental illness informed the research objectives and study design. Registered individuals who had been diagnosed with severe mental illness (ICD-10 F20–39) were eligible. Each person with severe mental illness was frequency-matched with up to four people without severe mental illness on age, sex, practice, and calendar year. The first coprimary outcome was change in weight (kg), as per all recorded weight measures in the electronic health record. The second coprimary outcome was the incidence of advice and referral to weight management services. We estimated weight trajectories using hierarchical mixed-effects linear regression models and the incidence of advice and referrals using zero-inflated Poisson regression models. Findings: We included 113 904 individuals (mean age 39·17 years [SD 12·38]), of whom 51 062 (44·8%) were male and 62 842 (55·2%) were female; 90 620 (79·6%) self-identified as White, 7430 (6·5%) as Black, 12 288 (10·8%) as Asian, 1983 (1·7%) as mixed, and 1583 (1·4%) as other. 90 879 (79·8%) individuals did not have severe mental illness; 23 025 (20·2%) individuals had received a diagnosis of severe mental illness: 11 039 (47·9%) had a schizophrenia spectrum disorder, 11 942 (51·9%) had bipolar disorder, and 44 (0·2%) had other psychoses. Weight in people with severe mental illness increased by 2·10 kg (95% CI 1·98–2·22; p<0·0001) at year 1 and by 5·55 kg (5·24–5·86; p<0·0001) at year 15, compared with 0·58 kg (0·51–0·65; p<0·0001) at year 1 and 1·62 kg (1·42–1·82; p<0·0001) at year 15 in people without severe mental illness. After adjusting for age, sex, race and ethnicity, socioeconomic status, alcohol consumption status, smoking status, and BMI, people with severe mental illness and a BMI of 25 kg/m2 or higher were 10% more likely to receive weight advice than people without severe mental illness (incidence rate ratio 1·10 [95% CI 1·07–1·13]; 8·51 × 10−10). There were no differences in the rates of referral to weight management programmes between people with and without severe mental illness. Interpretation: People with severe mental illness are more likely to gain weight rapidly after diagnosis than the general population, with effects lasting up to 15 years. Despite frequent advice to lose weight, weight gain is not matched with rates of referrals to services for weight management. Early intervention is crucial to reduce excess weight and associated cardiometabolic risks in this underserved patient group. Funding: None.
Dietary pattern adherence in association with changes in body composition and adiposity measurements in the UK Biobank study
Background: Unhealthy dietary patterns (DP) have been frequently linked to avoidable ill-health, mediated in part through higher body mass index. However it is unclear how these patterns relate to specific components of body composition or fat distribution, and whether this may explain reported gender differences in the relationship between diet and health. Methods: Data from 101,046 UK Biobank participants with baseline bioimpedance analysis and anthropometric measures and dietary information on two or more occasions were used, of which 21,387 participants had repeated measures at follow up. Multivariable linear regressions estimated the associations between DP adherence (categorised in quintiles Q1–Q5) and body composition measures adjusted for a range of demographic and lifestyle confounders. Results: After 8.1 years of follow-up, individuals with high adherence (Q5) to the DP showed significantly positive changes in fat mass (mean, 95 % CI): 1.26 (1.12–1.39) kg in men, 1.11 (0.88–1.35) kg in women vs low adherence (Q1) − 0.09 (− 0.28 to 0.10) kg in men and − 0.26 (− 0.42 to − 0.11) kg in women; as well as in waist circumference (Q5): 0.93 (0.63–1.22) cm in men and 1.94 (1.63, 2.25) cm in women vs Q1 − 1.06 (− 1.34 to − 0.78) cm in men and 0.27 (− 0.02 to 0.57) cm in women. Conclusion: Adherence to an unhealthy DP is positively associated with increased adiposity, especially in the abdominal region, which may help explain the observed associations with adverse health outcomes.
Associations Between Dietary Patterns and Incident Type 2 Diabetes: Prospective Cohort Study of 120,343 UK Biobank Participants
OBJECTIVE To identify dietary patterns (DPs) characterized by a set of nutrients of concern and their association with incident type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS A total of 120,343 participants from the U.K. Biobank study with at least two 24 h dietary assessments were studied. Reduced rank regression was used to derive DPs explaining variability in energy density, free sugars, saturated fat, and fiber intakes. We investigated prospective associations with T2D using Cox propor-tional hazard models. RESULTS Over 8.4 years of follow-up from the latest dietary assessment, 2,878 participants developed T2D. Two DPs were identified that jointly explained a total of 63% var-iation in four nutrients. DP1 was characterized by high intakes of chocolate and confectionery, butter, low-fiber bread, and sugars and preserves, and low intakes of fruits and vegetables. DP1 was linearly associated with T2D in multivariable models without BMI adjustment (per z score, hazard ratio [HR] 1.11 [95% CI 1.08–1.14]) and after BMI adjustment (HR 1.09 [95% CI 1.06–1.12]). DP2 was characterized by high intakes of sugar-sweetened beverages, fruit juice, table sugars and preserves, and low intakes of high-fat cheese and butter, but showed no clear association with T2D. There were significant interactions between both DPs and age, with increased risks among younger people in DP1 (HR 1.13 [95% CI 1.09–1.18]) and DP2 (HR 1.10 [95% CI 1.05–1.15]), as well as with DP1 and BMI, with increased risks among people with obesity (HR 1.11 [95% CI 1.07–1.16]). CONCLUSIONS A DP characterized by high intakes of chocolate and confectionery, butter, low-fiber bread, and added sugars, and low in fresh fruits and vegetables intake is associated with a higher incidence of T2D, particularly among younger people and those with obesity.
Associations between dietary patterns and the incidence of total and fatal cardiovascular disease and all-cause mortality in 116,806 individuals from the UK Biobank: a prospective cohort study
Background: Traditionally, studies investigating diet and health associations have focused on single nutrients. However, key nutrients co-exist in many common foods, and studies focusing solely on individual nutrients may obscure their combined effects on cardiovascular disease (CVD) and all-cause mortality. We aimed to identify food-based dietary patterns which operate through excess energy intake and explain high variability in energy density, free sugars, saturated fat, and fiber intakes and to investigate their association with total and fatal CVD and all-cause mortality. Methods: Detailed dietary data was collected using a 24-h online dietary assessment on two or more occasions (n = 116,806). We used reduced rank regression to derive dietary patterns explaining the maximum variance. Multivariable Cox-proportional hazards models were used to investigate prospective associations with all-cause mortality and fatal and non-fatal CVD. Results: Over an average of 4.9 years of follow-up, 4245 cases of total CVD, 838 cases of fatal CVD, and 3629 cases of all-cause mortality occurred. Two dietary patterns were retained that jointly explained 63% of variation in energy density, free sugars, saturated fat, and fiber intakes in total. The main dietary pattern was characterized by high intakes of chocolate and confectionery, butter and low-fiber bread, and low intakes of fresh fruit and vegetables. There was a positive linear association between the dietary pattern and total CVD [hazard ratio (HR) per z-score 1.07, 95% confidence interval (CI) 1.04–1.09; HRtotal CVD 1.40, 95% CI 1.31–1.50, and HRall-cause mortality 1.37, 95% CI 1.27–1.47 in highest quintile]. A second dietary pattern was characterized by a higher intakes of sugar-sweetened beverages, fruit juice, and table sugar/preserves. There was a non-linear association with total CVD risk and all-cause mortality, with increased risk in the highest quintile [HRtotal CVD 1.14, 95% CI 1.07–1.22; HRall-cause mortality 1.11, 95% CI 1.03–1.19]. Conclusions: We identified dietary patterns which are associated with increased risk of CVD and all-cause mortality. These results help identify specific foods and beverages which are major contributors to unhealthy dietary patterns and provide evidence to underpin food-based dietary advice to reduce health risks.
Adherence to international dietary recommendations in association with all-cause mortality and fatal and non-fatal cardiovascular disease risk: a prospective analysis of UK Biobank participants
Background: International dietary guidelines aim to reduce risks of all-cause mortality, cardiovascular disease (CVD), and fatal CVD often associated with poor dietary habits. However, most studies have examined associations with individual nutrients, foods, or dietary patterns, as opposed to quantifying the pooled health effects of adherence to international dietary recommendations. We investigated associations between total adherence to the World Health Organization (WHO) dietary recommendations for saturated fats, free sugars, fibre, and fruits and vegetables and all-cause mortality and fatal and non-fatal CVD. Methods: We included participants from the UK Biobank cohort recruited in 2006–2010, which provided at least two valid 24-h dietary assessments. We defined adherence to dietary recommendations as ≤ 10% saturated fats, ≤ 10% free sugars, ≥ 25 g/day fibre, and ≥ 5 servings of fruits and vegetables/day. Multivariable Cox-proportional hazards models were used to investigate prospective associations with all-cause mortality and fatal and non-fatal CVD. In cross-sectional analyses, multivariable linear regression was used to examine associations with cardiometabolic risk factors. Results: Among 115,051 participants (39–72 years), only 29.7%, 38.5%, 22.3%, and 9.5% met 0, 1, 2, or 3–4 recommendations, respectively. There was a lower risk of all-cause mortality among participants meeting more dietary recommendations (Ptrend < 0.001), with a significantly lower risk among participants meeting 2: HR 0.91 (95% confidence interval [CI] 0.85–0.97) and 3–4: HR 0.79 (95% CI 0.71–0.88) recommendations. There was no trend with CVD risk, but a significantly lower risk of fatal CVD with 3–4 recommendations: HR 0.78 (95% CI 0.61–0.98). Meeting more recommendations resulted in significant cross-sectional trends (Ptrend < 0.001) towards lower body fat, waist circumference, LDL cholesterol, apolipoprotein B, triglycerides, alkaline phosphatase, gamma glutammyltransferase, and hs-CRP, but higher glucose and aspartate aminotransferase. Conclusions: Meeting dietary recommendations is associated with additive reductions in premature mortality. Motivating and supporting people to adhere to dietary guidelines may help extend years of healthy life expectancy.
Describing a new food group classification system for UK biobank: analysis of food groups and sources of macro- and micronutrients in 208,200 participants
Purpose: The UK Biobank study collected detailed dietary data using a web-based self-administered 24 h assessment tool, the Oxford WebQ. We aimed to describe a comprehensive food grouping system for this questionnaire and to report dietary intakes and key sources of selected nutrients by sex and education. Methods: Participants with at least one valid 24-h questionnaire were included (n = 208,200). Dietary data were grouped based on the presence of nutrients as well as culinary use, processing, and plant/animal origin. For each food group, we calculated the contribution to energy intake, key macronutrients, and micronutrients. We also identified the top contributors to energy intake, free sugars and saturated fat by sex and education. Results: From the 93 food groups, the top five contributors to energy intake (in descending order) were: desserts/cakes/pastries; white bread; white pasta/rice; bananas/other fruit; semi-skimmed milk. Wine, beer, and fruit juices were the top beverage contributors to overall energy intake. Biscuits, and desserts/cakes/pastries were the highest contributors to free sugars, total fat, and saturated fat intakes, but also contributed to the calcium and iron intakes. Top contributors to energy, saturated fat, and free sugars were broadly similar by sex and education category, with small differences in average nutrient intakes across the population. Conclusion: This new food classification system will support the growing interest in the associations between food groups and health outcomes and the development of food-based dietary guidelines. Food group variables will be available to all users of the UK Biobank WebQ questionnaire.
Investigating the association between recorded smoking cessation interventions and smoking cessation in people living with cardiovascular disease using UK general practice data
Background: Smoking significantly increases the risk of cardiovascular diseases (CVD), yet quitting smoking after diagnosis of CVD can mitigate further negative impacts. However, encouraging smoking cessation remains a challenge for General Practitioners (GPs) with concerns regarding mental health. Since 2004, the UK’s Quality and Outcomes Framework (QOF) incentivises GP smoking cessation support. Despite this, a significant proportion of individuals diagnosed with CVD continue to smoke after diagnosis. This study aims to investigate the frequencies and types of smoking cessation interventions offered to people with CVD (defined as coronary heart disease (CHD) and stroke), with and without mental illness, and assess their association with successful cessation. Methods: This retrospective cohort study examined adults diagnosed with CHD or stroke using the QResearch general practice records database (1996–2019). We evaluated the frequency and types of smoking cessation interventions documented in patients’ records, including education, brief interventions, pharmacological support, referrals, and counselling. Logistic regression assessed the relationship between recorded interventions and smoking abstinence rates within the one-year post-index event, considering QOF incentives and mental illness presence. Results: While smoking cessation education was common in general practice settings, prescriptions for nicotine replacement therapy or other evidence-based interventions were comparatively low. CHD and stroke populations showed a significant association between any intervention and smoking cessation within one year (CHD: OR 1.41, 95% CI 1.36–1.45; stroke: OR 1.49, 95% CI 1.43–1.55). Education consistently correlated with higher cessation likelihoods, while other interventions were linked to lower rates. Individuals with common and serious mental illness were less likely to quit, irrespective of intervention. QOF implementation led to increased documentation of advice but not intensive support or treatment, with pre-QOF interventions associated with significantly increased abstinence likelihoods (CHD: OR 5.09, 95% CI 4.84–5.35; stroke: OR 4.44, 95% CI 4.07–4.86). Conclusions: Financial incentives for GP smoking cessation support outlined in QOF may not suffice to enhance methods that are more efficacious or improve cessation rates, especially among people with mental illness. Practical strategies that provide tangible support and treatment are needed for CVD patients, including those with mental illness, to facilitate successful cessation.
Association between ketone metabolism and the risk of depression: An observational and Mendelian randomization study
Background: Ketone bodies (KBs) can serve as an alternative fuel source to glucose for the brain. Pre-clinical evidence suggests that KBs have neuroprotective properties, which might benefit depression. Aims: This study aimed to examine the association between KBs and the risk of depression using observational and genetic approaches. Method: Observational studies analyzed data collected between 2006 and 2010 from 245,459 participants in the UK Biobank, with follow-up to 31 October 2022. Genetic studies were firstly performed using one-sample Mendelian randomization (MR) with individual-level data from the UK Biobank; secondly, two-sample MR was performed using summary-level data from the largest available genome-wide association studies. KBs were measured by β-hydroxybutyrate with nuclear magnetic resonance spectroscopy. Depression outcomes were measured by linked hospital-based clinical depression diagnosis and Patient Health Questionnaire-9 (PHQ-9). Cox proportional hazard models and linear regression were used to examine the association of KBs with depression incidence and severity, and to compare the risks between individuals in light nutritional ketosis (≥0.5 mmol/l) and those not. Results: Observational analyses showed that each SD increase in KBs was associated with a 6 % (95 % CI, 1.03–1.08) increase in PHQ-9 scores in the fully adjusted model. Patients with KBs above 0.5 mmol/l had a higher risk of depression (HR 1.57; 95 % CI, 1.13–2.17) compared to those with KBs <0.5 mmol/l. In one-sample MR, there were no significant associations between genetically predicted KBs and depression and PHQ-9 scores. In two-sample MR analyses, we found no evidence of KBs (IVW OR 1.06; 95 % CI, 0.91–1.24) with the risk of depression. Conclusions: There was observational evidence that higher KB concentration was associated with an increased risk of depression, but MR suggests this is not causal. The efficacy of ketone therapy for depression remains unclear and warrants further investigation.
Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials
Context The use of prebiotics and probiotics as a treatment for psychiatric conditions has gained interest due to their potential to modulate the gut-brain axis. This review aims to assess the effectiveness of these interventions in reducing symptoms of depression and anxiety in psychiatric populations. Objective The aim was to comprehensively review and appraise the effectiveness of prebiotic, probiotic, and synbiotic interventions in reducing clinical depression and anxiety symptoms. Data Sources Systematic searches were conducted across Embase, Medline, PsycINFO, CINAHL, Cochrane Library, and Science Citation Index from database inception to May 22, 2023. Data Extraction Randomized controlled trials investigating prebiotic, probiotic, or synbiotic interventions for treating clinical depression or anxiety symptoms in clinical samples were included. Data were extracted on study characteristics, intervention details, and outcome measures. The Cochrane Collaboration Tool was used to assess the risk of bias. Data Analysis The standardized mean difference (SMD) was calculated using Hedge's g as the metric of effect size. A random-effects model was applied to estimate pooled effect sizes with 95% CIs. Subgroup analyses were performed based on study characteristics, methodological factors, and intervention types. Sensitivity analyses excluded studies with a high risk of bias. Results Twenty-three RCTs involving 1401 patients met the inclusion criteria, with 20 trials providing sufficient data for meta-analysis. Of these, 18 trials investigated probiotics for depression, 9 trials assessed probiotics for anxiety, and 3 trials examined prebiotics for depression. Probiotics demonstrated a significant reduction in depression symptoms (SMD: -0.96; 95% CI: -1.31, -0.61) and a moderate reduction in anxiety symptoms (SMD: -0.59; 95% CI: -0.98, -0.19). Prebiotics did not show a significant effect on depression (SMD: -0.28; 95% CI: -0.61, 0.04). High heterogeneity was observed across studies, and subgroup analyses indicated that study duration and probiotic formulations contributed to the variation in effect sizes. Conclusion Probiotics showed substantial reductions in depression symptoms and moderate reductions in anxiety symptoms. Prebiotics showed a nonsignificant trend toward reducing depression. An adjunctive mental health treatment approach that diagnoses, monitors, and treats the gut microbiome alongside traditional pharmacological treatment holds promise for clinical practice. Systematic Review Registration PROSPERO registration no. CRD42023424136.
Dose-Dependent Association Between Body Mass Index and Mental Health and Changes Over Time
IMPORTANCE Overweight and obesity affect 340 million adolescents worldwide and constitute a risk factor for poor mental health. Understanding the association between body mass index (BMI) and mental health in adolescents may help to address rising mental health issues; however, existing studies lack comprehensive evaluations spanning diverse countries and periods. OBJECTIVE To estimate the association between BMI and mental health and examine changes over time from 2002 to 2018. DESIGN, SETTING, AND PARTICIPANTS This was a repeated multicountry cross-sectional study conducted between 2002 and 2018 and utilizing data from the Health Behaviour in School-aged Children (HBSC) survey in Europe and North America. The study population consisted of more than 1 million adolescents aged 11 to 15 years, with all surveyed children included in the analysis. Data were analyzed from October 2022 to March 2023. MAIN OUTCOMES AND MEASURES Mental health difficulties were measured by an 8-item scale for psychological concerns, scoring from 0 to 32, where a higher score reflects greater psychosomatic issues. BMI was calculated using weight divided by height squared and adjusted for age and sex. Data were fitted by multilevel generalized additive model. Confounders included sex, living with parents, sibling presence, academic pressure, the experience of being bullied, family affluence, screen time, and physical activity. RESULTS Our analysis of 1 036 869 adolescents surveyed from 2002 to 2018, with a mean (SD) age of 13.55 (1.64) years and comprising 527 585 girls (50.9%), revealed a consistent U-shaped association between BMI and mental health. After accounting for confounders, adolescents with low body mass and overweight or obesity had increased psychosomatic symptoms compared to those with healthy weight (unstandardized β, 0.14; 95% CI, 0.08 to 0.19; unstandardized β, 0.27; 95% CI, 0.24 to 0.30; and unstandardized β, 0.62; 95% CI, 0.56 to 0.67, respectively), while adolescents with underweight had fewer symptoms (unstandardized β, −0.18; 95% CI, −0.22 to −0.15). This association was observed across different years, sex, and grade, indicating a broad relevance to adolescent mental health. Compared to 2002, psychosomatic concerns increased significantly in 2006 (unstandardized β, 0.19; 95% CI, 0.11 to 0.26), 2010 (unstandardized β, 0.14; 95% CI, 0.07 to 0.22), 2014 (unstandardized β, 0.48; 95% CI, 0.40 to 0.56), and 2018 (unstandardized β, 0.82; 95% CI, 0.74 to 0.89). Girls reported significantly higher psychosomatic concerns than boys (unstandardized β, 2.27; 95% CI, 2.25 to 2.30). Compared to primary school, psychosomatic concerns rose significantly in middle school (unstandardized β, 1.15; 95% CI, 1.12 to 1.18) and in high school (unstandardized β, 2.12; 95% CI, 2.09 to 2.15). CONCLUSIONS AND RELEVANCE Our study revealed a U-shaped association between adolescent BMI and mental health, which was consistent across sex and grades and became stronger over time. These insights emphasize the need for targeted interventions addressing body image and mental health, and call for further research into underlying mechanisms.