Population attributable fraction: names, types and issues with incorrect interpretation of relative risks

Proportion of venous thromboembolism attributed to recognized prothrombotic genotypes in men and women

Background

Data on the proportion of venous thromboembolism (VTE) risk attributed to prothrombotic genotypes in men and women are limited.

Objectives

We aimed to estimate the population attributable fraction (PAF) of VTE for recognized, common prothrombotic genotypes in men and women using a population-based case cohort.

Methods

Cases with incident VTE (n = 1493) and a randomly sampled subcohort (n = 13,069) were derived from the Tromsø study (1994-2012) and the Trøndelag Health Study (1995-2008) cohorts. DNA samples were genotyped for 17 single-nucleotide polymorphisms (SNPs) previously associated with VTE. PAFs with 95% bias-corrected CIs (based on 10,000 bootstrap samples) were estimated for SNPs significantly associated with VTE, and a 6-SNP cumulative model was constructed for both sexes.

Results

In women, the individual PAFs for SNPs included in the cumulative model were 16.9% for ABO (rs8176719), 17.6% for F11 (rs2036914), 15.1% for F11 (rs2289252), 8.7% for FVL (rs6025), 6.0% for FGG (rs2066865), and 0.2% for F2 (rs1799963). The cumulative PAF for this 6-SNP model was 37.8%. In men, the individual PAFs for SNPs included in the cumulative model were 21.3% for ABO, 12.2% for F11 (rs2036914), 10.4% for F11 (rs2289252), 7.5% for FVL, 7.8% for FGG, and 1.1% for F2. This resulted in a cumulative PAF in men of 51.9%.

Conclusion

Our findings in a Norwegian population suggest that 52% and 38% of the VTEs can be attributed to known prothrombotic genotypes in men and women, respectively.

Associations between BMI in youth and site-specific cancer in men-A cohort study with register linkage

OBJECTIVE

This study examined BMI in young men and incident site-specific cancer to estimate population attributable fractions due to BMI based on projected obesity prevalence.

METHODS

A population-based cohort study with measured height and weight at age 18. Cox regression models assessed linear associations for BMI and included age, year, and site of conscription as well as parental level of education as covariates.

RESULTS

Primary analyses were performed in 1,489,115 men, of whom 78,217 subsequently developed cancer during a mean follow-up of 31 years. BMI was linearly associated with risk of developing all 18 site-specific cancers assessed (malignant melanoma; leukemia; myeloma; Hodgkin lymphoma; non-Hodgkin lymphoma; and cancer in the lungs, head and neck, central nervous system, thyroid, esophagus, stomach, pancreas, liver and gallbladder, colon, rectum, kidney, and bladder), in some instances evident at BMI levels usually defined as normal (20-25 kg/m2 ). Higher BMI was associated with lower risk of prostate cancer. The highest hazard ratios and population attributable fractions were seen for some gastrointestinal cancers.

CONCLUSIONS

This study reports linear associations between BMI at age 18 and subsequent site-specific cancers, calling for rapid action to stem the obesity epidemic and to prepare the health care system for steep increases in cancer cases.

Socioeconomic differences in dietary habits in Italy before and during COVID-19 pandemic: secondary analysis of a nationwide cross-sectional study

BACKGROUND

Several socioeconomic conditions may influence subjects' adherence to healthy eating habits. Food consumption may be influenced by external stress during crisis periods; however, the effects of these events on food habits are difficult to predict. Also, a pandemic crisis like the recent COVID-19 pandemic may have influenced dietary habits and food consumption. The objective of this study was to compare the dietary habits of Italian people before the COVID-19 pandemic with those belonging to the year 2020 in a nationwide population sample.

MATERIALS AND METHODS

Information on dietary habits has been obtained from the multi-purpose survey on families' "Aspects of daily life", carried out in Italy by the Italian National Statistics Institute (ISTAT). We analyzed data coming from 2016 and 2020 editions of the survey (43,000 subjects each year). We used population attributable fraction (PAF) adjusted for age, defined as the proportional reduction in unhealthy diet that would occur if all participants had had a higher education, assuming higher educated individuals as more socially advantaged. Prevalence association for each dietary exposition has been calculated through logistic regression.

RESULTS

Looking at aggregated data from 2016 and 2020 both men and women showed a high prevalence of unhealthy dietary habits. Regarding men, excessive consumption of eggs, pork meat, and bovine meat was characterized by a PAF attributable to socioeconomic conditions to an extent greater than 30%. Women showed the same trend. Focusing on different years of investigation, in 2020, during the COVID-19 pandemic, men and women increased their consumption of eggs, cooked fats, snacks, and sweets, and reduced consumption of fruits and vegetables. Additionally, women increased the assumption of dietary products and meat. Both sexes registered an increase in overweight and obese subjects in 2020.

CONCLUSIONS

To our knowledge, this study was the first in our country to use a yearly, nationwide sample to analyze dietary habits by examining specific types of various foods on a nationwide scale and establishing a correlation between these habits and the COVID-19 pandemic. Our results showed unbalanced dietary habits of the Italian population with an excess of consumption of several foods like eggs, cooked fats snacks, and sweets with low consumption of fruits and vegetables. Socioeconomic differences influence food choices but in a complex way since they seemed to affect some wrong dietary habits but not others, especially regarding fruits and vegetables assumption where differences were less evident among social classes. Outside stressors like a crisis period such as the COVID-19 pandemic seem to have an important role in both men and women regarding the assumption of so-called "junk food".

Diet Quality and Mortality among Chinese Adults: Findings from the China Health and Nutrition Survey

The association between diet quality and all-cause mortality in Chinese population is unclear. We aimed to study the associations of three a priori diet quality indices-including the Diet Quality Index-International (DQI-I), Chinese Healthy Eating Index (CHEI), and energy-adjusted Dietary Inflammatory Index (E-DII)-and their included components with all-cause mortality. We used baseline data from the 2004, 2006, 2009, and 2011 waves of the China Health and Nutrition Survey (CHNS). We used a multivariable-adjusted Cox model to examine the associations between DQI-I, CHEI, and E-DII with all-cause mortality. During a mean of 7 years of follow-up, a total of 461 deaths occurred among 12,914 participants. For DQI-I, there were significant inverse associations with mortality for the variety score (HRQ4 vs. Q1 = 0.69, 95%CI = 0.52-0.92) and overall balance score (HR>0 vs. 0 = 0.81, 95%CI = 0.66-0.91). The adequacy score of CHEI was associated with 40% less risk of all-cause mortality (HRQ4 vs. Q1 = 0.60, 95%CI = 0.43-0.84). E-DII was not associated with mortality. An estimated 20.1%, 13.9%, and 31.3% of total mortality would be averted if the DQI-I variety score, DQI-I overall balance score, and CHEI adequacy score improved from the bottom to the top quartile, respectively. Improving diet quality, especially improving diet variety and adequacy, and having a more balanced diet may reduce all-cause mortality in Chinese adults.

Antenatal depression across trimesters as a risk for postpartum depression and estimation of the fraction of postpartum depression attributable to antenatal depression: A systematic review and meta-analysis of cohort studies

OBJECTIVE

This meta-analysis aimed at estimating the prevalence of postpartum depression (PPD) at different postpartum timepoints in women with antenatal depression (AD) in the three trimesters. We also examined the association between AD and PPD, and estimated the population attributable fraction of PPD to AD.

METHODS

This systematic review and meta-analysis identified cohort studies that determined the prevalence of PPD in women who had AD, and those that examined the association between AD and PPD from PubMed, Embase, MEDLINE, CINAHL and PsycINFO. Articles were appraised using the modified Newcastle Ottawa Scale and data were analyzed using Comprehensive Meta-Analysis.

RESULTS

Eighty-eight (88) cohort studies with a combined sample size of 1,042,448 perinatal women contributed to the meta-analysis. About 37% pregnant women who had AD, later had PPD. Those with AD had four times higher odds of developing PPD (OR: 4.58; 95% CI = 3.52-5.96). The odds of having PPD were higher when AD was observed in the first or third trimester compared to the second trimester. About 12.8% of PPD cases were attributable to AD.

CONCLUSION

The findings should inform future clinical guidelines on the screening, the frequency of screening, and follow-up care in maternal-mental health.

Non-occupational physical activity and risk of cardiovascular disease, cancer and mortality outcomes: a dose-response meta-analysis of large prospective studies

OBJECTIVE

To estimate the dose-response associations between non-occupational physical activity and several chronic disease and mortality outcomes in the general adult population.

DESIGN

Systematic review and cohort-level dose-response meta-analysis.

DATA SOURCES

PubMed, Scopus, Web of Science and reference lists of published studies.

ELIGIBILITY CRITERIA

Prospective cohort studies with (1) general population samples >10 000 adults, (2) ≥3 physical activity categories, and (3) risk measures and CIs for all-cause mortality or incident total cardiovascular disease, coronary heart disease, stroke, heart failure, total cancer and site-specific cancers (head and neck, myeloid leukaemia, myeloma, gastric cardia, lung, liver, endometrium, colon, breast, bladder, rectum, oesophagus, prostate, kidney).

RESULTS

196 articles were included, covering 94 cohorts with >30 million participants. The evidence base was largest for all-cause mortality (50 separate results; 163 415 543 person-years, 811 616 events), and incidence of cardiovascular disease (37 results; 28 884 209 person-years, 74 757 events) and cancer (31 results; 35 500 867 person-years, 185 870 events). In general, higher activity levels were associated with lower risk of all outcomes. Differences in risk were greater between 0 and 8.75 marginal metabolic equivalent of task-hours per week (mMET-hours/week) (equivalent to the recommended 150 min/week of moderate-to-vigorous aerobic physical activity), with smaller marginal differences in risk above this level to 17.5 mMET-hours/week, beyond which additional differences were small and uncertain. Associations were stronger for all-cause (relative risk (RR) at 8.75 mMET-hours/week: 0.69, 95% CI 0.65 to 0.73) and cardiovascular disease (RR at 8.75 mMET-hours/week: 0.71, 95% CI 0.66 to 0.77) mortality than for cancer mortality (RR at 8.75 mMET-hours/week: 0.85, 95% CI 0.81 to 0.89). If all insufficiently active individuals had achieved 8.75 mMET-hours/week, 15.7% (95% CI 13.1 to 18.2) of all premature deaths would have been averted.

CONCLUSIONS

Inverse non-linear dose-response associations suggest substantial protection against a range of chronic disease outcomes from small increases in non-occupational physical activity in inactive adults. PROSPERO registration number CRD42018095481.

Age at diagnosis modifies associations of type 2 diabetes with cancer incidence and mortality: a retrospective matched-cohort study

AIMS/HYPOTHESIS

The age-specific associations between type 2 diabetes and cancer risk are not fully understood. The aim of this study was to assess how age at diagnosis modifies the associations between type 2 diabetes and cancer risk.

METHODS

We used data from the Yinzhou Health Information System, and included 42,279 individuals who were newly diagnosed with type 2 diabetes between 2010 and 2014, as well as 166,010 age- and sex-matched control individuals without diabetes who were selected randomly from the electronic health records of the entire population. Patients were divided into four age groups according to age at diagnosis: <50, 50-59, 60-69 and ≥70 years. Stratified Cox proportional hazards regression models, with age as the time scale, were used to estimate the HRs and 95% CIs for the associations of type 2 diabetes with the risks of overall and site-specific cancers. Population-attributable fractions were also calculated for outcomes associated with type 2 diabetes.

RESULTS

During median follow-up periods of 9.20 and 9.32 years, we identified 15,729 incident cancer cases and 5383 cancer deaths, respectively. Patients diagnosed with type 2 diabetes before 50 years of age had the highest relative risks of cancer incidence and mortality, with HRs (95% CI) of 1.35 (1.20, 1.52) for overall cancer incidence, 1.39 (1.11, 1.73) for gastrointestinal cancer incidence, 2.02 (1.50, 2.71) for overall cancer mortality, and 2.82 (1.91, 4.18) for gastrointestinal cancer mortality. Risk estimates decreased gradually with each decade increase in diagnostic age. The population-attributable fractions for overall cancer and gastrointestinal cancer mortality also decreased with increasing age.

CONCLUSIONS/INTERPRETATION

The associations of type 2 diabetes with cancer incidence and mortality varied by age at diagnosis, with a higher relative risk among patients who were diagnosed at a younger age.

Population attributable fraction of hypertension for dementia: global, regional, and national estimates for 186 countries

Background

Quantifying the proportion of dementia attributable to highly prevalent modifiable risk factors, such as hypertension, is important in informing effective dementia prevention strategies. We aim to quantify the population attributable fraction (PAF) of hypertension for dementia (the proportion of dementia cases that would not occur if hypertension was eliminated) at global, regional, and national levels.

Methods

In this study, we searched international and governmental websites for global, regional, and national data reporting population hypertension (according to 10-year age categories) and dementia prevalence. MEDLINE was searched for studies reporting the risk of dementia from age at hypertension diagnosis from database inception to December 31, 2022. Longitudinal observational studies with >500 participants reporting hazard ratios by age at hypertension diagnosis for risk of future all-cause dementia were eligible for inclusion. Studies excluded had cross-sectional methodology, specific vascular dementia or 'cognitive impairment' outcomes, and no age-specific metrics of association reported. The PAF of hypertension for dementia was calculated globally and for each country and region worldwide.

Findings

Data from the Global Burden of Disease, United Nations Population Prospectus, NCD Risk Factor Collaboration, UK Biobank, and Atherosclerosis Risk in Communities Study were obtained. 186 countries reported dementia and hypertension prevalence data. The global PAF of hypertension for dementia was 15.8% [95% Credible Interval (CI), 8.8%-22.7%]. Latin America and the Caribbean (18.0% [95% CI, 9.4%-26.6%]), and Europe (17.2% [95% CI, 9.6%-24.7%]) had the highest PAF of hypertension for dementia. Hypertension diagnosed between the ages of 30-44 had the highest age-specific global attributable fraction for dementia (8.4% [95% CI, 3.4%-13.5%]), followed by ages 45-54 (2.92% [ 95% CI, 0.96%-4.88%]), 55-64 (2.59% [95% CI, 1.15%-4.03%]) and 65-74 (1.82% [95% CI, -2.31%-5.96%]).

Interpretation

The population attributable risk of hypertension for dementia is 15.8%, suggesting that optimal detection and treatment, particularly at midlife, has the potential to markedly reduce the global burden of dementia.

Funding

Wellcome Trust; Health Research Board of Ireland; Alzheimer's Association.

Variation in smoking attributable all-cause mortality across municipalities in Belgium, 2018: application of a Bayesian approach for small area estimations

BACKGROUND

Smoking is one of the leading causes of preventable mortality and morbidity worldwide, with the European Region having the highest prevalence of tobacco smoking among adults compared to other WHO regions. The Belgian Health Interview Survey (BHIS) provides a reliable source of national and regional estimates of smoking prevalence; however, currently there are no estimates at a smaller geographical resolution such as the municipality scale in Belgium. This hinders the estimation of the spatial distribution of smoking attributable mortality at small geographical scale (i.e., number of deaths that can be attributed to tobacco). The objective of this study was to obtain estimates of smoking prevalence in each Belgian municipality using BHIS and calculate smoking attributable mortality at municipality level.

METHODS

Data of participants aged 15 + on smoking behavior, age, gender, educational level and municipality of residence were obtained from the BHIS 2018. A Bayesian hierarchical Besag-York-Mollie (BYM) model was used to model the logit transformation of the design-based Horvitz-Thompson direct prevalence estimates. Municipality-level variables obtained from Statbel, the Belgian statistical office, were used as auxiliary variables in the model. Model parameters were estimated using Integrated Nested Laplace Approximation (INLA). Deviance Information Criterion (DIC) and Conditional Predictive Ordinate (CPO) were computed to assess model fit. Population attributable fractions (PAF) were computed using the estimated prevalence of smoking in each of the 589 Belgian municipalities and relative risks obtained from published meta-analyses. Smoking attributable mortality was calculated by multiplying PAF with age-gender standardized and stratified number of deaths in each municipality.

RESULTS

BHIS 2018 data included 7,829 respondents from 154 municipalities. Smoothed estimates for current smoking ranged between 11% [Credible Interval 3;23] and 27% [21;34] per municipality, and for former smoking between 4% [0;14] and 34% [21;47]. Estimates of smoking attributable mortality constituted between 10% [7;15] and 47% [34;59] of total number of deaths per municipality.

CONCLUSIONS

Within-country variation in smoking and smoking attributable mortality was observed. Computed estimates should inform local public health prevention campaigns as well as contribute to explaining the regional differences in mortality.

Prevalence of hyperuricemia and the population attributable fraction of modifiable risk factors: Evidence from a general population cohort in China

Data on updated hyperuricemia prevalence in Beijing-Tianjin-Hebei (BTH) region in China, which is one of the world-class urban agglomerations, is sparse. Overweight/obesity, alcohol consumption, smoking and sedentary behavior are modifiable risk factors (MRFs) for elevated serum uric acid (SUA), but their population attributable fractions (PAFs) for hyperuricemia is still unclear. Using baseline data from the BTH Physical Examination General Population Cohort, we calculated the crude- and adjusted-prevalence of hyperuricemia based on the 30,158 participants aged 18–80 years. Hyperuricemia was defined as SUA >420 μmol/L in men and >360 μmol/L in women, or currently use of uric acid lowering drugs. Overweight/obesity, alcohol consumption, smoking and sedentary behavior were considered as MRFs and their adjusted PAFs were estimated. The prevalence of hyperuricemia was 19.37%, 27.72% in men and 10.69% in women. The PAFs and 95% confidence intervals for overweight, obesity were 16.25% (14.26–18.25%) and 12.08% (11.40–12.77%) in men, 13.95% (12.31–15.59%) and 6.35% (5.97–6.74%) in women, respectively. Alcohol consumption can explain 4.64% (2.72–6.56%) hyperuricemia cases in men, but with no statistical significance in women. Cigarette smoking contributed to 3.15% (1.09–5.21%) cases in men, but a much lower fraction in women (0.85%, 0.49–1.22%). Compared with sedentary time <2 h per day, the PAFs of 2–4 h, 4–6 h, and more than 6 h per day were 3.14% (1.34–4.93%), 6.72% (4.44–8.99%) and 8.04% (4.95–11.13%) in men, respectively. Sedentary time was not found to be associated with hyperuricemia in women. These findings concluded that hyperuricemia is prevalent in this representative Chinese adult general population with substantial sex difference. Four MRFs (overweight/obesity, alcohol consumption, cigarette smoking and sedentary behavior) accounted for a notable proportion of hyperuricemia cases. The PAF estimations enable the exploration of the expected proportion of hyperuricemia cases that could be prevented if the MRFs were removed, which warrants the public health significance of life-style intervention.

Association Between Physical Activity and Risk of Depression: A Systematic Review and Meta-analysis

Importance

Depression is the leading cause of mental health-related disease burden and may be reduced by physical activity, but the dose-response relationship between activity and depression is uncertain.

Objective

To systematically review and meta-analyze the dose-response association between physical activity and incident depression from published prospective studies of adults.

Data Sources

PubMed, SCOPUS, Web of Science, PsycINFO, and the reference lists of systematic reviews retrieved by a systematic search up to December 11, 2020, with no language limits. The date of the search was November 12, 2020.

Study Selection

We included prospective cohort studies reporting physical activity at 3 or more exposure levels and risk estimates for depression with 3000 or more adults and 3 years or longer of follow-up.

Data Extraction and Synthesis

Data extraction was completed independently by 2 extractors and cross-checked for errors. A 2-stage random-effects dose-response meta-analysis was used to synthesize data. Study-specific associations were estimated using generalized least-squares regression and the pooled association was estimated by combining the study-specific coefficients using restricted maximum likelihood.

Main Outcomes and Measures

The outcome of interest was depression, including (1) presence of major depressive disorder indicated by self-report of physician diagnosis, registry data, or diagnostic interviews and (2) elevated depressive symptoms established using validated cutoffs for a depressive screening instrument.

Results

Fifteen studies comprising 191 130 participants and 2 110 588 person-years were included. An inverse curvilinear dose-response association between physical activity and depression was observed, with steeper association gradients at lower activity volumes; heterogeneity was large and significant (I2 = 74%; P < .001). Relative to adults not reporting any activity, those accumulating half the recommended volume of physical activity (4.4 marginal metabolic equivalent task hours per week [mMET-h/wk]) had 18% (95% CI, 13%-23%) lower risk of depression. Adults accumulating the recommended volume of 8.8 mMET hours per week had 25% (95% CI, 18%-32%) lower risk with diminishing potential benefits and higher uncertainty observed beyond that exposure level. There were diminishing additional potential benefits and greater uncertainty at higher volumes of physical activity. Based on an estimate of exposure prevalences among included cohorts, if less active adults had achieved the current physical activity recommendations, 11.5% (95% CI, 7.7%-15.4%) of depression cases could have been prevented.

Conclusions and Relevance

This systematic review and meta-analysis of associations between physical activity and depression suggests significant mental health benefits from being physically active, even at levels below the public health recommendations. Health practitioners should therefore encourage any increase in physical activity to improve mental health.

Risk factors for development of long-term mood and anxiety disorder after pediatric traumatic brain injury: a population-based, birth cohort analysis

OBJECTIVES

The objective of this study was to identify characteristics associated with an increased risk of anxiety and mood disorder prior to 25 years of age, in children who sustained a traumatic brain injury (TBI) prior to age 10.

METHODS

This population-based study identified 562 TBI cases from a 1976-1982 birth cohort in Olmsted County, Minnesota. TBI cases were manually confirmed and classified by injury severity. Separate Cox proportional hazards regression models were fit to estimate the association of TBI and secondary non-TBI related characteristics with the risk of a subsequent clinically determined anxiety or mood disorder. Multivariable-adjusted population attributable risk (PAR) estimates were calculated for TBI characteristics.

RESULTS

Older age at initial TBI and extracranial injury at time of initial TBI were significantly associated with an increased risk of anxiety (adjusted HR [95% CI]: 1.33 [1.16, 1.52] per 1-year increase and 2.41 [1.26, 4.59]), respectively. Older age at initial TBI was significantly associated with an increased risk of a mood disorder (adjusted HR 1.17 [1.08-1.27]).

CONCLUSION

In individuals sustaining a TBI prior to age 10, age at injury greater than 5 years old was the largest contributor to development of a mood or anxiety disorder.

Methods Matter: A Comparative Review of Health Risk Assessments for Ambient Air Pollution in Switzerland

Objectives: Air pollution health risk assessments (AP-HRAs) provide a method to quantify health effects for entire populations. In Switzerland, AP-HRAs are included in Swiss assessments for Transport Externalities (STEs), ordered by public authorities since the 1990s. This study aimed to describe the differences among national and international AP-HRAs for Switzerland. Methods: We compared input data, approaches and results across AP-HRAs over time. Results and input data for each AP-HRA were expressed as a ratio compared to the most recent STE (in most cases STE-2010). Results: Substantial variation across AP-HRAs was found. For all-cause adult mortality attributed to particulate matter (the most frequent outcome-pollutant pair), the ratio in HRAs oscillated from 0.40 to 2.09 (times the STE-2010 value). Regarding input data, the ratio ranged from 0.69 to 1.26 for population exposure, from 0 to 1.81 for counterfactual scenario, from 0.96 to 1.13 for concentration-response function and from 1.03 to 1.13 for baseline health data. Conclusion: This study demonstrates that methods matter for AP-HRAs. Transparent and possibly standardized reporting of key input data and assumptions should be promoted to facilitate comparison of AP-HRAs.

Modelling the potential health and economic benefits of reducing population sitting time in Australia

Background

Strong evidence indicates that excessive time spent sitting (sedentary behaviour) is detrimentally associated with multiple chronic diseases. Sedentary behaviour is prevalent among adults in Australia and has increased during the COVID-19 pandemic. Estimating the potential health benefits and healthcare cost saving associated with reductions in population sitting time could be useful for the development of public health initiatives.

Methods

A sedentary behaviour model was developed and incorporated into an existing proportional, multi-state, life table Markov model (ACE-Obesity Policy model). This model simulates the 2019 Australian population (age 18 years and above) and estimates the incidence, prevalence and mortality of five diseases associated with sedentary behaviour (type 2 diabetes, stroke, endometrial, breast and colorectal cancer). Key model inputs included population sitting time estimates from the Australian National Health Survey 2014–2015, healthcare cost data from the Australian Institute of Health and Welfare (2015) and relative risk estimates assessed by conducting literature reviews and meta-analyses. Scenario analyses estimated the potential change in disease incidence as a result of changes in population sitting time. This, in turn, resulted in estimated improvements in long term health outcomes (Health-adjusted life years (HALYs)) and healthcare cost-savings.

Results

According to the model, if all Australian adults sat no more than 4 h per day, the total HALYs gained would be approximately 17,211 with health care cost savings of approximately A$185 million over one year. Under a more feasible scenario, where sitting time was reduced in adults who sit 4 or more hours per day by approximately 36 min per person per day (based on the results of the Stand Up Victoria randomised controlled trial), potential HALYs gained were estimated to be 3,670 and healthcare cost saving could reach A$39 million over one year.

Conclusions

Excessive sedentary time results in considerable population health burden in Australia. This paper describes the development of the first Australian sedentary behaviour model that can be used to predict the long term consequences of interventions targeted at reducing sedentary behaviour through reductions in sitting time. These estimates may be used by decision makers when prioritising healthcare resources and investing in preventative public health initiatives.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-022-01276-2.

Fraction of COVID-19 hospitalizations and deaths attributable to chronic diseases

Evidence shows that chronic diseases are associated with COVID-19 severity and death. This study aims to estimate the fraction of hospitalizations and deaths from COVID-19 attributable to chronic diseases associated to poor nutrition and smoking among adults who tested positive to COVID-19 in Mexico. We analyzed 1,006,541 adults aged ≥20 who tested positive for COVID-19 from March 23 to December 5, 2020. Six chronic diseases were considered: obesity, chronic obstructive pulmonary disease (COPD), hypertension, diabetes, cardiovascular disease, and chronic kidney disease (CKD). We calibrated the database using a bias quantification method to consider undiagnosed disease cases. To estimate the total impact of multiple diseases, we defined a multimorbidity variable according to the number of diseases. Risks of hospitalization and death were estimated with Poisson regression models and used to calculate population attributable fractions (PAFs). Chronic diseases accounted for to 25.4% [95% CI: 24.8%-26.1%], 28.3% (95% CI: 27.8%-28.7%) and 15.3% (95% CI: 14.9%-15.7%) of the hospitalizations among adults below 40, 40-59, and 60 years and older, respectively. For COVID-19-related deaths, 50.1% (95% CI: 48.6%-51.5%), 40.5% (95% CI: 39.7%-41.3%), and 18.7% (95% CI, 18.0%-19.5%) were attributable to chronic diseases in adults under 40, 40-59, and 60 years and older, respectively. Chronic diseases linked to poor nutrition and smoking could have contributed to a large burden of hospitalization and deaths from COVID-19 in Mexico, particularly among younger adults. Medical and structural interventions to curb chronic disease incidence and facilitate disease control are urgently needed.

Hospitalisations for pelvic inflammatory disease in young Aboriginal women living in remote Australia: the role of chlamydia and gonorrhoea

OBJECTIVE

Aboriginal women living in remote Australia experience a high burden of both chlamydia and gonorrhoea infections and disproportionately high rates of pelvic inflammatory disease (PID). We estimated for the first time the fraction of PID attributable to these infections in young Aboriginal women living in these settings.

METHODS

Using published data from two large Australian studies (2002-2013; 2010-2014), we calculated the fraction of emergency department presentations and hospitalisations for PID attributable to chlamydia and/or gonorrhoea infection in Aboriginal women aged 16-29 years living in remote Australia. We used a Monte Carlo simulation to estimate the mean and 95% CIs for the assumed prevalence and population attributable fractions for PID for infection stratifications (chlamydia only, gonorrhoea only and dual infection) as well as for any infection (chlamydia and/or gonorrhoea). Additional outputs were calculated for chlamydia infection with/without gonorrhoea coinfection, and vice versa.

RESULTS

The prevalence of chlamydia only was 12.9% (95% CI: 11.6% to 14.2%), gonorrhoea only was 7.8% (95% CI: 6.6% to 8.9%) and dual infection was 6.5% (95% CI: 5.8% to 7.2%); rate ratios of PID were 1.9 (95% CI: 1.5 to 2.3), 5.2 (95% CI: 4.3 to 6.4) and 4.6 (95% CI: 3.8 to 5.5), respectively. The overall fraction of PID attributable to chlamydia and/or gonorrhoea was 40.2% (95% CI: 36.0% to 44.4%); any gonorrhoea was 33.4% (95% CI: 29.2% to 37.8%) and any chlamydia was 20.6% (95% CI: 16.9% to 24.6%).

CONCLUSION

Our study demonstrates the importance of calculating the fraction of PID related to chlamydia and gonorrhoea in the local context, demonstrating the major contribution gonorrhoea makes to PID hospitalisations among Australian Aboriginal women living in remote settings. To significantly and sustainably reduce the unacceptable rate of PID in this population, strategies are urgently needed to improve timely testing and treatment and recognition and management of PID in primary care.

Customized GROW vs INTERGROWTH-21st birthweight standards to identify small for gestational age associated perinatal outcomes at term

BACKGROUND

Fetal growth restriction is associated with stillbirth and other adverse pregnancy outcomes, and use of the correct weight standard is an essential proxy indicator of growth status and perinatal risk.

OBJECTIVE

We sought to assess the performance of two international birthweight standards for their ability to identify perinatal morbidity and mortality indicators associated with small for gestational age (SGA) infants at term.

STUDY DESIGN

This retrospective cohort study used data from a multi-center perinatal quality initiative including a multi-ethnic dataset of 125,826 births from 2012-2017. Of the singleton term births, 92,622 had complete outcome data including stillbirth, neonatal death, 5-minute Apgar <7, neonatal glucose instability and need for newborn transfer to a higher level of care or NICU admission. The customized (GROW) and INTERGROWTH-21^st (IG21) birthweight standards were applied to determine SGA (<10^th centile) according to their respective methods and formulae. Associations with adverse outcomes were expressed as relative risk (RR) with 95% confidence interval (CI) and population attributable fraction (PAF).

RESULTS

GROW classified 9,578 (10.3%) and IG21 classified 4,079 (4.4%) pregnancies as SGA, respectively. For all of the outcomes assessed, GROW identified more SGA infants with adverse outcomes than IG21, including more stillbirths, perinatal deaths, low Apgar scores, glucose instability, newborn seizure and transfers to a higher level of care. Thirteen of the 27 stillbirths (48%) that were SGA by either method were identified as SGA by GROW but not by IG21. Similarly, additional cases of all other adverse outcome indicators were identified by GROW as SGA, while only in one category (glucose instability) did IG21 identify 9 of 295 cases (3.1%) which were not identified as SGA by GROW.

CONCLUSION

Customized assessment using GROW results in increased identification of small for gestational age term babies that are at significantly increased risk of an array of adverse pregnancy outcomes.

The risk of venous thromboembolism attributed to established prothrombotic genotypes

BACKGROUND

The proportion of venous thromboembolism (VTE) events that can be attributed to established prothrombotic genotypes has been scarcely investigated in the general population. We aimed to estimate the proportion of VTEs in the population that could be attributed to established prothrombotic genotypes using a population-based case-cohort.

METHODS

Cases with incident VTE (n=1,493) and a randomly sampled sub-cohort (n=13,069) were derived from the Tromsø Study (1994-2012) and the Nord-Trøndelag Health (HUNT) Study (1995-2008). DNA-samples were genotyped for 17 single nucleotide polymorphism (SNPs) associated with VTE. Hazard ratios with 95% confidence intervals (CIs) were estimated in Cox regression models. Population attributable fraction (PAF) with 95% bias-corrected CIs (based on 10,000 bootstrap samples) were estimated using a cumulative model where SNPs significantly associated with VTE were added one-by-one in ranked order of the individual PAFs.

RESULTS

Six SNPs were significantly associated with VTE (rs1799963 [Prothrombin], rs2066865 [FGG], rs6025 [FV Leiden], rs2289252 [F11], rs2036914 [F11] and rs8176719 [ABO]. The cumulative PAF for the six-SNP model was 45.3% (95% CI 19.7-71.6) for total VTE and 61.7% (95% CI 19.6-89.3) for unprovoked VTE. The PAF for prothrombotic genotypes was higher for DVT (52.9%) than for PE (33.8%), and higher for those aged <70 years (66.1%) than for those aged ≥70 years (24.9%).

CONCLUSIONS

Our findings suggest that 45-62% of all VTE events in the population can be attributed to known prothrombotic genotypes. The PAF of established prothrombotic genotypes was higher in DVT than in PE, and higher in the young than in the elderly.

What is the likely impact on surgical site infections in Australian hospitals if smoking rates are reduced? A cost analysis

INTRODUCTION

Assisting smokers to quit before surgery reduces surgical site infection (SSI) risk. The short-term economic benefits of reducing SSIs by embedding tobacco dependence treatment in Australian hospitals are unknown. Estimated annual number of SSIs prevented, and hospital bed-days (HBD) and costs saved from reducing smoking before surgery are calculated.

METHODS

The most recent number of surgical procedures and SSI rates for Australia were sourced. The number of smokers and non-smokers having a SSI were calculated using the UK Royal College of Physicians reported adjusted odds ratio (1.79), and the proportion of SSIs attributable to smoking calculated. The potential impact fraction was used to estimate reductions in SSIs and associated HBDs and costs from reducing the smoking rates among surgical patients from 23.9% to 10% or 5% targets. Uncertainty around the final estimates was calculated using probabilistic sensitivity analysis.

RESULTS

In 2016-17, approximately 40,593 (95% UI 32,543, 50,239) people having a surgical procedure in Australia experienced a SSI leading to 101,888 extra days (95% UI 49,988, 200,822) in hospital. If the smoking rate among surgical patients was reduced to 10%, 3,580 (95% UI 2,312, 5,178) SSIs would be prevented, and 8,985 (95% UI 4,094, 19,153) HBDs and $19.1M (95% UI $7.7M, $42.5M) saved in one year. If the smoking rate was reduced to 5%, 4,867 (95% UI 3,268, 6,867) SSIs would be prevented, and 12,217 (95% UI 5,614, 25,642) HBDs and $26.0M (95% UI $10.8M, $57.0M) would be saved.

CONCLUSIONS

The findings suggest achieving smoking rate targets of 10% or 5% would provide substantial short-term health and economic benefits through reductions in SSIs. Embedding tobacco dependence treatment in Australian hospitals would provide value for money by reducing costs and improving clinical quality and safety. A more comprehensive, modelled economic evaluation synthesising the best available evidence is needed to confirm findings.

The comparative effect of exposure to various risk factors on the risk of hyperuricaemia: diet has a weak causal effect

BACKGROUND

Prevention of hyperuricaemia (HU) is critical to the prevention of gout. Understanding causal relationships and relative contributions of various risk factors to hyperuricemia is therefore important in the prevention of gout. Here, we use attributable fraction to compare the relative contribution of genetic, dietary, urate-lowering therapy (ULT) and other exposures to HU. We use Mendelian randomisation to test for the causality of diet in urate levels.

METHODS

Four European-ancestry sample sets, three from the general population (n = 419,060) and one of people with gout (n = 6781) were derived from the Database of Genotypes and Phenotypes (ARIC, FHS, CARDIA, CHS) and UK Biobank. Dichotomised exposures to diet, genetic risk variants, BMI, alcohol, diuretic treatment, sex and age were used to calculate adjusted population and average attributable fractions (PAF/AAF) for HU (≥0.42 mmol/L [≥7 mg/dL]). Exposure to ULT was also assessed in the gout cohort. Two sample Mendelian randomisation was done in the UK Biobank using dietary pattern-associated genetic variants as exposure and serum urate levels as outcome.

RESULTS

Adherence to dietary recommendations, BMI (< 25 kg/m²), and absence of the SLC2A9 rs12498742 urate-raising allele produced PAFs for HU of 20 to 24%, 59 to 69%, and 57 to 64%, respectively, in the three non-gout cohorts. In the gout cohort, diet, BMI, SLC2A9 rs12498742 and ULT PAFs for HU were 12%, 49%, 48%, and 63%, respectively. Mendelian randomisation demonstrated weak causal effects of four dietary habits on serum urate levels (e.g. preferentially drinking skim milk increased urate, β = 0.047 mmol/L, P = 3.78 × 10^-8). These effects were mediated by BMI, and they were not significant (P ≥ 0.06) in multivariable models assessing the BMI-independent effect of diet on urate.

CONCLUSIONS

Diet has a relatively minor role in determining serum urate levels and HU. In gout, the use of ULT was the largest attributable fraction tested for HU.

Population Attributable Fractions of Modifiable Risk Factors for Nonsyndromic Orofacial Clefts: A Prospective Cohort Study From the Japan Environment and Children's Study

Background

Population impact of modifiable risk factors on orofacial clefts is still unknown. This study aimed to estimate population attributable fractions (PAFs) of modifiable risk factors for nonsyndromic cleft lip with or without cleft palate (CL±P) and cleft palate only (CP) in Japan.

Methods

We conducted a prospective cohort study using data from the Japan Environment and Children’s Study, which recruited pregnant women from 2011 to 2014. We estimated the PAFs of maternal alcohol consumption, psychological distress, maternal active and passive smoking, abnormal body mass index (BMI) (<18.5 and ≥25 kg/m²), and non-use of a folic acid supplement during pregnancy for nonsyndromic CL±P and CP in babies.

Results

A total of 94,174 pairs of pregnant women and their single babies were included. Among them, there were 146 nonsyndromic CL±P cases and 41 nonsyndromic CP cases. The combined adjusted PAF for CL±P of the modifiable risk factors excluding maternal alcohol consumption was 34.3%. Only maternal alcohol consumption was not associated with CL±P risk. The adjusted PAFs for CL±P of psychological distress, maternal active and passive smoking, abnormal BMI, and non-use of a folic acid supplement were 1.4% (95% confidence interval [CI], −10.7 to 15.1%), 9.9% (95% CI, −7.0 to 26.9%), 10.8% (95% CI, −9.9 to 30.3%), 2.4% (95% CI, −7.5 to 14.0%), and 15.1% (95% CI, −17.8 to 41.0%), respectively. We could not obtain PAFs for CP due to the small sample size.

Conclusions

We reported the population impact of the modifiable risk factors on CL±P, but not CP. This study might be useful in planning the primary prevention of CL±P.

Is a liveable city a healthy city? Health impacts of urban and transport planning in Vienna, Austria

Each year, The Economist Intelligence Unit (EIU) computes the Global Liveability Index and determines the most liveable cities around the world. Vienna, Austria, was ranked by the EIU as the most liveable city worldwide in 2018 and 2019. However, the relationship between a liveable as well as healthy and environmentally-just city has not been previously explored. To explore whether the most liveable city is also a healthy and environmentally-just one, we estimated the premature mortality burden related to non-compliance with international exposure level recommendations for physical activity (PA), air pollution (PM_2.5 and NO₂), road traffic noise, green space and heat for Vienna, as well as its distribution by socioeconomic status (SES). We applied the Urban and TranspOrt Planning Health Impact Assessment (UTOPHIA) methodology and estimated the annual mortality, life expectancy (LE) and economic impact of non-compliance with exposure guidelines for the Viennese adult population ≥ 20 years. We compared current with recommended exposure levels, quantified the association between exposures and mortality and calculated attributable health impact fractions. Eight percent of premature mortality (i.e. 1239 deaths, 95% CI: 679-1784) was estimated to be attributable to non-compliance with the recommended exposure levels. Seventy-six percent of the attributable premature mortality was due to PM_2.5 exposure and insufficient PA. Non-compliance also resulted in an average of 199 days of LE lost for the adult population (95% CI: 111-280) and an economic impact of 4.6 (95% CI: 2.5-6.7) billion 2015€ annually. Overall, residents of lower SES neighbourhoods faced higher risk of premature mortality due to higher exposure to NO₂, road traffic noise, heat and less green space. Despite high liveability standards according to EIU definition, a considerable premature mortality burden was attributable to non-compliance with exposure recommendations, and socioeconomic inequalities were estimated. Although the exposure attributable mortality burden was lower than in other European cities and local Viennese policies favour the reduction of motorized traffic, alongside the promotion of active and public transport and urban greening, there is room for further alignment of liveability, environmental health and justice objectives.

Potential gains in life expectancy from reducing amenable mortality among people diagnosed with serious mental illness in the United Kingdom

BACKGROUND

To estimate the potential gain in life expectancy from addressing modifiable risk factors for all-cause mortality (excluding suicide and deaths from accidents or violence) across specific serious mental illness (SMI) subgroups, namely schizophrenia, schizoaffective disorders, and bipolar disorders in a Western population.

METHODS

We have used relative risks from recent meta-analyses to estimate the population attribution fraction (PAF) due to specific modifiable risk factors known to be associated with all-cause mortality within SMI. The potential gain in life expectancy at birth, age 50 and age 65 years were assessed by estimating the combined effect of modifiable risk factors from different contextual levels (behavioural, healthcare, social) and accounting for the effectiveness of existing interventions tackling these factors. Projections for annual gain in life expectancy at birth during a two-decade was estimated using the Annual Percentage Change (APC) formula. The predicted estimates were based on mortality rates for year 2014-2015.

RESULTS

Based on the effectiveness of existing interventions targeting these modifiable risk factors, we estimated potential gain in life expectancy at birth of four (bipolar disorders), six (schizoaffective disorders), or seven years (schizophrenia). The gain in life expectancy at age 50 years was three (bipolar disorders) or five (schizophrenia and schizoaffective disorders) years. The projected gain in life expectancy at age 65 years was three (bipolar disorders) or four (schizophrenia and schizoaffective disorders) years.

CONCLUSIONS

The implementation of existing interventions targeting modifiable risk factors could narrow the current mortality gap between the general and the SMI populations by 24% (men) to 28% (women). These projections represent ideal circumstances and without the limitation of overestimation which often comes with PAFs.

Changing the urban design of cities for health: The superblock model

BACKGROUND

Car-dependent city planning has resulted in high levels of environmental pollution, sedentary lifestyles and increased vulnerability to the effects of climate change. The Barcelona Superblock model is an innovative urban and transport planning strategy that aims to reclaim public space for people, reduce motorized transport, promote sustainable mobility and active lifestyles, provide urban greening and mitigate effects of climate change. We estimated the health impacts of implementing this urban model across Barcelona.

METHODS

We carried out a quantitative health impact assessment (HIA) study for Barcelona residents ≥20 years (N = 1,301,827) on the projected Superblock area level (N = 503), following the comparative risk assessment methodology. We 1) estimated expected changes in (a) transport-related physical activity (PA), (b) air pollution (NO₂), (c) road traffic noise, (d) green space, and (e) reduction of the urban heat island (UHI) effect through heat reductions; 2) scaled available risk estimates; and 3) calculated attributable health impact fractions. Estimated endpoints were preventable premature mortality, changes in life expectancy and economic impacts.

RESULTS

We estimated that 667 premature deaths (95% CI: 235-1,098) could be prevented annually through implementing the 503 Superblocks. The greatest number of preventable deaths could be attributed to reductions in NO₂ (291, 95% PI: 0-838), followed by noise (163, 95% CI: 83-246), heat (117, 95% CI: 101-137), and green space development (60, 95% CI: 0-119). Increased PA for an estimated 65,000 persons shifting car/motorcycle trips to public and active transport resulted in 36 preventable deaths (95% CI: 26-50). The Superblocks were estimated to result in an average increase in life expectancy for the Barcelona adult population of almost 200 days (95% CI: 99-297), and result in an annual economic impact of 1.7 billion EUR (95% CI: 0.6-2.8).

DISCUSSION

The Barcelona Superblocks were estimated to help reduce harmful environmental exposures (i.e. air pollution, noise, and heat) while simultaneously increase PA levels and access to green space, and thereby provide substantial health benefits. For an equitable distribution of health benefits, the Superblocks should be implemented consistently across the entire city. Similar health benefits are expected for other cities that face similar challenges of environmental pollution, climate change vulnerability and low PA levels, by adopting the Barcelona Superblock model.

A Review of Methodological Approaches for Developing Diagnostic Algorithms for Diabetes Screening

BACKGROUND AND PURPOSE

Diagnostic algorithms are invaluable tools for screening diabetes. This review aimed to evaluate and identify the most robust methodological approaches for developing diagnostic algorithms for screening diabetes.

METHODS

Following a literature search, methodological quality of algorithm development studies was evaluated using the TRIPOD guidelines (Collins, Reitsma, Altman, & Moons, 2015).

RESULTS

Methods used for developing the algorithms included logistic regression models, classification and regression trees, Random Forest and TreeNet, Artificial Neural Networks, and Naïve Bayes. Methodological issues for algorithm development studies were related to handling of missing values, reporting recruitment methods, categorization of continuous variables, and statistical controls.

CONCLUSIONS

Most studies exhibited critical methodological flaws and poor adherence to reporting standards. Diabetes screening algorithms can easily be availed electronically and utilized by nurses at minimal cost even in underserved areas.

Hypertension Risk with Abacavir Use among HIV-Infected Individuals: A Nationwide Cohort Study

PURPOSE

A high risk of cardiovascular disease (CVD) is reported for HIV-infected individuals. While a link between abacavir and CVD risk is suggested, an association between abacavir and hypertension remains unclear. This study evaluated hypertension risk with abacavir use in comparison to non-abacavir antiretroviral treatment (ART).

MATERIALS AND METHODS

From a nationwide cohort of HIV-infected individuals on their initial ART, 6493 who were free of hypertension at baseline were analyzed. The use of ART was treated as a time-varying covariate measured as a daily unit. Incidence rate of hypertension was calculated, and Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) with 95% confidence interval (CI) of incident hypertension overall and among subgroups.

RESULTS

From the 6493 participants, 24072 person-years (PY) of follow-up were contributed during 2008-2016. The incidence rates of hypertension were 4.6 and 3.6 per 100 PY for abacavir and non-abacavir ART users, respectively. The population attributable fraction of abacavir use on hypertension was 12%. Abacavir exposure did not elevate the risk of hypertension among overall study population [HR, 1.2 (95% CI, 1.0-1.4), p=0.061]. However, those with poor ART adherence, defined as a medication possession ratio <50% [HR, 1.9 (95% CI, 1.5-2.4), p<0.0001] or requiring prophylactic antibiotics [HR, 1.2 (95% CI, 1.0-1.3), p=0.023], were at risk of hypertension induced by abacavir, as were men, individuals aged ≥40 years, and patients visiting tertiary hospitals in urban areas.

CONCLUSION

When present, poor ART adherence, requiring prophylactic antibiotics, male sex, and older age may warrant additional concern for hypertension in patients treated with abacavir.

Estimates of burden and consequences of infants born small for gestational age in low and middle income countries with INTERGROWTH-21st standard: analysis of CHERG datasets

Objectives To estimate small for gestational age birth prevalence and attributable neonatal mortality in low and middle income countries with the INTERGROWTH-21^st birth weight standard.Design Secondary analysis of data from the Child Health Epidemiology Reference Group (CHERG), including 14 birth cohorts with gestational age, birth weight, and neonatal follow-up. Small for gestational age was defined as infants weighing less than the 10th centile birth weight for gestational age and sex with the multiethnic, INTERGROWTH-21^st birth weight standard. Prevalence of small for gestational age and neonatal mortality risk ratios were calculated and pooled among these datasets at the regional level. With available national level data, prevalence of small for gestational age and population attributable fractions of neonatal mortality attributable to small for gestational age were estimated.Setting CHERG birth cohorts from 14 population based sites in low and middle income countries.Main outcome measures In low and middle income countries in the year 2012, the number and proportion of infants born small for gestational age; number and proportion of neonatal deaths attributable to small for gestational age; the number and proportion of neonatal deaths that could be prevented by reducing the prevalence of small for gestational age to 10%.Results In 2012, an estimated 23.3 million infants (uncertainty range 17.6 to 31.9; 19.3% of live births) were born small for gestational age in low and middle income countries. Among these, 11.2 million (0.8 to 15.8) were term and not low birth weight (≥2500 g), 10.7 million (7.6 to 15.0) were term and low birth weight (<2500 g) and 1.5 million (0.9 to 2.6) were preterm. In low and middle income countries, an estimated 606 500 (495 000 to 773 000) neonatal deaths were attributable to infants born small for gestational age, 21.9% of all neonatal deaths. The largest burden was in South Asia, where the prevalence was the highest (34%); about 26% of neonatal deaths were attributable to infants born small for gestational age. Reduction of the prevalence of small for gestational age from 19.3% to 10.0% in these countries could reduce neonatal deaths by 9.2% (254 600 neonatal deaths; 164 800 to 449 700).Conclusions In low and middle income countries, about one in five infants are born small for gestational age, and one in four neonatal deaths are among such infants. Increased efforts are required to improve the quality of care for and survival of these high risk infants in low and middle income countries.

The modelled impact of increases in physical activity: the effect of both increased survival and reduced incidence of disease

Physical activity can affect ‘need’ for healthcare both by reducing the incidence rate of some diseases and by increasing longevity (increasing the time lived at older ages when disease incidence is higher). However, it is common to consider only the first effect, which may overestimate any reduction in need for healthcare. We developed a hybrid micro-simulation lifetable model, which made allowance for both changes in longevity and risk of disease incidence, to estimate the effects of increases in physical activity (all adults meeting guidelines) on measures of healthcare need for diseases for which physical activity is protective. These were compared with estimates made using comparative risk assessment (CRA) methods, which assumed that longevity was fixed. Using the lifetable model, life expectancy increased by 95 days (95% uncertainty intervals: 68–126 days). Estimates of the healthcare need tended to decrease, but the magnitude of the decreases were noticeably smaller than those estimated using CRA methods (e.g. dementia: change in person-years, −0.6%, 95% uncertainty interval −3.7% to +1.6%; change in incident cases, −0.4%, −3.6% to +1.9%; change in person-years (CRA methods), −4.0%, −7.4% to −1.6%). The pattern of results persisted under different scenarios and sensitivity analyses. For most diseases for which physical activity is protective, increases in physical activity are associated with decreases in indices of healthcare need. However, disease onset may be delayed or time lived with disease may increase, such that the decreases in need may be relatively small and less than is sometimes expected.