Emily Carnahan

The Burden Attributable to Mental and Substance Use Disorders as Risk Factors for Suicide: Findings from the Global Burden of Disease Study 2010

Background The Global Burden of Disease Study 2010 (GBD 2010) identified mental and substance use disorders as the 5th leading contributor of burden in 2010, measured by disability adjusted life years (DALYs). This estimate was incomplete as it excluded burden resulting from the increased risk of suicide captured elsewhere in GBD 2010s mutually exclusive list of diseases and injuries. Here, we estimate suicide DALYs attributable to mental and substance use disorders. Methods Relative-risk estimates of suicide due to mental and substance use disorders and the global prevalence of each disorder were used to estimate population attributable fractions. These were adjusted for global differences in the proportion of suicide due to mental and substance use disorders compared to other causes then multiplied by suicide DALYs reported in GBD 2010 to estimate attributable DALYs (with 95% uncertainty). Results Mental and substance use disorders were responsible for 22.5 million (14.8–29.8 million) of the 36.2 million (26.5–44.3 million) DALYs allocated to suicide in 2010. Depression was responsible for the largest proportion of suicide DALYs (46.1% (28.0%–60.8%)) and anorexia nervosa the lowest (0.2% (0.02%–0.5%)). DALYs occurred throughout the lifespan, with the largest proportion found in Eastern Europe and Asia, and males aged 20–30 years. The inclusion of attributable suicide DALYs would have increased the overall burden of mental and substance use disorders (assigned to them in GBD 2010 as a direct cause) from 7.4% (6.2%–8.6%) to 8.3% (7.1%–9.6%) of global DALYs, and would have changed the global ranking from 5th to 3rd leading cause of burden. Conclusions Capturing the suicide burden attributable to mental and substance use disorders allows for more accurate estimates of burden. More consideration needs to be given to interventions targeted to populations with, or at risk for, mental and substance use disorders as an effective strategy for suicide prevention.

The global burden of musculoskeletal conditions for 2010: an overview of methods

The objective of this paper is to provide an overview of methods used for estimating the burden from musculoskeletal (MSK) conditions in the Global Burden of Diseases 2010 study. It should be read in conjunction with the disease-specific MSK papers published in Annals of Rheumatic Diseases. Burden estimates (disability-adjusted life years (DALYs)) were made for five specific MSK conditions: hip and/or knee osteoarthritis (OA), low back pain (LBP), rheumatoid arthritis (RA), gout and neck pain, and an ‘other MSK conditions’ category. For each condition, the main disabling sequelae were identified and disability weights (DW) were derived based on short lay descriptions. Mortality (years of life lost (YLLs)) was estimated for RA and the rest category of ‘other MSK’, which includes a wide range of conditions such as systemic lupus erythematosus, other autoimmune diseases and osteomyelitis. A series of systematic reviews were conducted to determine the prevalence, incidence, remission, duration and mortality risk of each condition. A Bayesian meta-regression method was used to pool available data and to predict prevalence values for regions with no or scarce data. The DWs were applied to prevalence values for 1990, 2005 and 2010 to derive years lived with disability. These were added to YLLs to quantify overall burden (DALYs) for each condition. To estimate the burden of MSK disease arising from risk factors, population attributable fractions were determined for bone mineral density as a risk factor for fractures, the occupational risk of LBP and elevated body mass index as a risk factor for LBP and OA. Burden of Disease studies provide pivotal guidance for governments when determining health priority areas and allocating resources. Rigorous methods were used to derive the increasing global burden of MSK conditions.

The global burden attributable to low bone mineral density

Introduction The Global Burden of Disease Study 2010 estimated the worldwide health burden of 291 diseases and injuries and 67 risk factors by calculating disability-adjusted life years (DALYs). Osteoporosis was not considered as a disease, and bone mineral density (BMD) was analysed as a risk factor for fractures, which formed part of the health burden due to falls. Objectives To calculate (1) the global distribution of BMD, (2) its population attributable fraction (PAF) for fractures and subsequently for falls, and (3) the number of DALYs due to BMD. Methods A systematic review was performed seeking population-based studies in which BMD was measured by dual-energy X-ray absorptiometry at the femoral neck in people aged 50 years and over. Age- and sex-specific mean ± SD BMD values (g/cm2) were extracted from eligible studies. Comparative risk assessment methodology was used to calculate PAFs of BMD for fractures. The theoretical minimum risk exposure distribution was estimated as the age- and sex-specific 90th centile from the Third National Health and Nutrition Examination Survey (NHANES III). Relative risks of fractures were obtained from a previous meta-analysis. Hospital data were used to calculate the fraction of the health burden of falls that was due to fractures. Results Global deaths and DALYs attributable to low BMD increased from 103 000 and 3 125 000 in 1990 to 188 000 and 5 216 000 in 2010, respectively. The percentage of low BMD in the total global burden almost doubled from 1990 (0.12%) to 2010 (0.21%). Around one-third of falls-related deaths were attributable to low BMD. Conclusions Low BMD is responsible for a growing global health burden, only partially representative of the real burden of osteoporosis.

Mortality attributable to smoking in Vietnamese men in 2008

OBJECTIVE Smoking prevalence among Vietnamese men is among the highest in the world. Our aim was to provide estimates of tobacco attributable mortality to support tobacco control policies. METHOD We used the Peto-Lopez method using lung cancer mortality to derive a Smoking Impact Ratio (SIR) as a marker of cumulative exposure to smoking. SIRs were applied to relative risks from the Cancer Prevention Study, Phase II. Prevalence-based and hybrid methods, using the SIR for cancers and chronic obstructive pulmonary disease and smoking prevalence for all other outcomes, were used in sensitivity analyses. RESULTS When lung cancer was used to measure cumulative smoking exposure, 28% (95% uncertainty interval 24-31%) of all adult male deaths (>35 years) in Vietnam in 2008 were attributable to smoking. Lower estimates resulted from prevalence-based methods [24% (95% uncertainty interval 21-26%)] with the hybrid method yielding intermediate estimates [26% (95% uncertainty interval 23-28%)]. CONCLUSION Despite uncertainty in these estimates of attributable mortality, tobacco smoking is already a major risk factor for death in Vietnamese men. Given the high current prevalence of smoking, this has important implications not only for preventing the uptake of tobacco but also for immediate action to adopt and enforce stronger tobacco control measures.

Validation of a new predictive risk model: measuring the impact of the major modifiable risks of death for patients and populations.

BackgroundModifiable risks account for a large fraction of disease and death, but clinicians and patients lack tools to identify high risk populations or compare the possible benefit of different interventions.MethodsWe used data on the distribution of exposure to 12 major behavioral and biometric risk factors inthe US population, mortality rates by cause, and estimates of the proportional hazards of risk factor exposure from published systematic reviews to develop a risk prediction model that estimates an adult’s 10 year mortality risk compared to a population with optimum risk factors. We compared predicted risk to observed mortality in 8,241 respondents in NHANES 1988-1994 and NHANES 1999-2004 with linked mortality data up to the end of 2006.ResultsPredicted risk showed good discrimination with an area under the receiver operating characteristic (ROC) curve of 0.84 (standard error 0.01) for women and 0.84 (SE 0.01) for men. Across deciles of predicted risk, mortality was accurately predicted in men ((Χ2 statistic = 12.3 for men, p=0.196) but slightly overpredicted in the highest decile among women (Χ2 statistic = 22.8, p=0.002). Mortality risk was highly concentrated; for example, among those age 30-44 years, 5.1 % (95 % CI 4.1 % - 6.0 %) of the male and 5.9 % (95 % CI 4.8 % - 6.9 %) of the female population accounted for 25 % of the risk of death.ConclusionThe risk model accurately predicted mortality in a representative sample of the US population and could be used to help inform patient and provider decision-making, identify high risk groups, and monitor the impact of efforts to improve population health.

Burden attributable to suboptimal breastfeeding: a cross-country analysis of country-specific trends and their relation to child health inequalities

Abstract Background In 2010, more than 7·7 million children died before their fifth birthday. Over 98% of these deaths occurred in developing countries. Within these countries, child mortality is concentrated in the lowest wealth quintile. Breastfeeding is a proven child health intervention available to almost all mothers and it does not require additional health infrastructure. However, breastfeeding prevalence remains low in many developing countries. This paper seeks to examine how breastfeeding prevalence and associated disease burden vary across countries and how breastfeeding interventions may affect child health inequalities. Methods Using data from more than 400 health and nutrition surveys and spatial temporal regression models, the prevalence of suboptimal breastfeeding was estimated for 137 developing countries from 1990 to 2012. These estimates were compared against WHO infant feeding recommendations and combined with effect sizes from existing literature to estimate associated disease burden using a standard comparative risk assessment approach. These data were disaggregated by wealth quintile and compared with coverage rates for other child health interventions to assess how improved rates of breastfeeding may affect child health inequalities. Findings In 2010, the estimated prevalence of exclusive breastfeeding ranged from 3·5% in Djibouti to 77·3% in Rwanda. The estimated proportion of child disability-adjusted life-years attributable to breastfeeding is 7·6% at the global level and as high as 20·2% in Swaziland. Breastfeeding is a leading childhood risk factor in all developing countries and consistently ranks higher than water and sanitation. Within countries, breastfeeding practices vary considerably across wealth quintiles. Interpretation Breastfeeding is an effective child health intervention that does not require extensive health-system infrastructure. Improvements in rates of exclusive and continued breastfeeding can contribute to the reduction of child mortality inequalities in developing countries. Active promotion of breastfeeding can prevent a large proportion of child deaths and disease burden. Funding Bill & Melinda Gates Foundation.

Validation of a new predictive risk model for mortality using Framingham Heart Study data

Abstract Background The Institute for Health Metrics and Evaluation (IHME) developed a risk model to estimate 10-year mortality risk compared with a population with optimum risk factors in adults aged 30 years and older. IHME used data on exposure distributions of 12 behavioural and biometric risks in the US population, mortality rates by cause, and estimates of the proportional hazards of risk factor exposure from systematic reviews. The model has been validated using National Health and Nutrition Examination Survey (NHANES) data collected during 1988–94 and 1999–2004 (n=8331). Methods We will use data from participants attending the Framingham Heart Study (FHS) Offspring Examination 7 (1998–2001) and the Original Cohort Examination 20 (1986–90) to further validate the 10-year mortality risk model. These examinations were chosen since risk factors used in the IHME development mortality risk model were measured in these examinations. FHS participants aged 30 years and older at the time of examination will be included. Model performance will be assessed by (a) area under the curve to assess the ability of the model to discriminate between FHS participants who did and did not die within 10 years; and (b) Hosmer-Lemeshow goodness-of-fit tests comparing the FHS-observed mortality rate with the model-predicted mortality risk. Findings The FHS validation cohort consists of 3500 participants (mean age 62·4 years); 55% are women. Unlike NHANES, the FHS cohort sample is predominantly white. The FHS cohort is approximately 10·6 years (95% CI 10·1–11·1) older than NHANES, on average; FHS and NHANES have 55% and 53% females, respectively. The observed mortality rate is 14·3% (95% CI 13·2–15·5) in FHS and 8·4% (7·8–9·0) in NHANES cohort samples. We will present the findings of the validation on the FHS participants and compare with NHANES validation results. Interpretation Adequate performance of the risk model when applied to FHS, a sample with characteristics somewhat different from NHANES, will further support its validity and usefulness in the US population. Funding National Heart, Lungs and Blood Institute at the National Institutes of Health (2 N01-HC-25195-06).