Objective To evaluate the global burden of musculoskeletal (MSK) disorders, as well as the five common conditions, and their relevant risk factors from 1990 to 2019. Design Data from the Global Burden of Disease Study 2019 were used in this study. Setting and participants Individuals of all ages and genders from 204 countries and territories in 21 regions. Main outcome measures The outcomes were the numbers and age-standardised rates (ASRs) of incident cases, deaths and disability-adjusted life-years (DALYs) of MSK disorders. The average annual percent changes (AAPCs) in the ASRs were calculated using joinpoint regression analysis to estimate the trends. Results There were 322.75 million incident cases, 117.54 thousand deaths and 150.08 million DALYs of MSK disorders in 2019. The age-standardised incidence rate and age-standardised DALY rate in 2019 (incidence: AAPC=−0.32, 95% CI −0.34 to −0.31; DALYs: AAPC=−0.05, 95% CI −0.06 to −0.04) were lower than those in 1990. However, the age-standardised death rate showed a stable trend (AAPC 0.05, 95% CI −0.05 to 0.15) from 1990 to 2019. The peak age of onset and DALYs of MSK disorders was 50–54 years in 2019. The burden of MSK disorders in females was much higher than that in males (1.29 times more incident cases, 2.24 times more deaths and 1.45 times more DALYs in females than in males). A significant negative correlation was observed between the AAPCs in the ASRs and the Sociodemographic Index (SDI) score. Occupational risk exhibited the highest contribution to MSK disorders, and tobacco use and high body mass index were also major risk factors. Conclusions This study demonstrates that the burden of MSK disorders tends to be lower in high-SDI regions than in lower-SDI regions. Strengthening the effectiveness of preventive measures against occupational risks may reduce the burden of MSK disorders.

Aims: Sleep disturbance is an important factor in the pathophysiology and progression of psychiatric disorders, but whether it is a cause, or a downstream effect is still not clear. Methods: To investigate causal relationships between three sleep-associated traits and seven psychiatric diseases, we used genetic variants related to insomnia, chronotype and sleep duration to perform a two-sample bidirectional Mendelian randomisation analysis. Summary-level data on psychiatric disorders were extracted from the Psychiatric Genomics Consortium. Effect estimates were obtained by using the inverse-variance-weighted (IVW), weights modified IVW, weighted-median methods, MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO) test and Robust Adjusted Profile Score (RAPS). Results: The causal odds ratio (OR) estimate of genetically determined insomnia was 1.33 (95% confidence interval (CI) 1.22–1.45; p = 5.03 × 10⁻¹¹) for attention-deficit/hyperactivity disorder (ADHD), 1.31 (95% CI 1.25–1.37; p = 6.88 × 10⁻³¹) for major depressive disorder (MDD) and 1.32 (95% CI 1.23–1.40; p = 1.42 × 10⁻¹⁶) for post-traumatic stress disorder (PTSD). There were suggestive inverse associations of morningness chronotype with risk of MDD and schizophrenia (SCZ). Genetically predicted sleep duration was also nominally associated with the risk of bipolar disorder (BD). Conversely, PTSD and MDD were associated with an increased risk of insomnia (OR = 1.06, 95% CI 1.03–1.10, p = 7.85 × 10⁻⁴ for PTSD; OR = 1.37, 95% CI 1.14–1.64; p = 0.001 for MDD). A suggestive inverse association of ADHD and MDD with sleep duration was also observed. Conclusions: Our findings provide evidence of potential causal relationships between sleep disturbance and psychiatric disorders. This suggests that abnormal sleep patterns may serve as markers for psychiatric disorders and offer opportunities for prevention and management in psychiatric disorders.

Background. Leukemia is a common malignancy that has four main subtypes and is a threat to human health. Understanding the epidemiological status of leukemia and its four main subtypes globally is important for allocating appropriate resources, guiding clinical practice, and furthering scientific research. Methods. Average annual percentage changes (AAPCs) were calculated to estimate the change trends of age-standardized rates (ASRs) from 1990 to 2019 in 204 countries and territories. The risk factors for leukemia death and disability-adjusted life-year (DALY) were also analyzed. In addition, the future trends in ASRs were projected through 2030. Results. The total number of incident cases, deaths, and DALYs from leukemia in 2019 was 0.64, 0.33, and 11.66 million, respectively. Decreasing trends in age-standardized incidence rate (ASIR), the age-standardized death rate (ASDR), and age-standardized DALY rate were detected on a global level while increasing trends in ASIR were detected in the high-sociodemographic index (SDI) regions. The leukemia burden was heavier in males than in females. By cause, acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL) were more likely to impose a burden on the elderly, while acute lymphoblastic leukemia (ALL) showed a greater impact in the younger population. A significant positive correlation was observed between SDI and AAPC in ASIR, while SDI was negatively correlated with AAPCs in both ASDR and age-standardized DALY rate. Smoking remained the most significant risk factor associated with leukemia-related death and DALY, especially in males. Similar deaths and DALYs were caused by smoking and high body mass index (BMI) in females. Future projections through 2030 estimated that ASIR and ASDR will continue to increase, while the DALY rate is predicted to decline. Conclusions. Patterns and trends of leukemia burden are correlated with SDI. The estimated contributions to leukemia deaths indicate that timely measures are needed to reduce smoking and obesity.

Background: The aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer.Methods: A literature search of PubMed and Embase databases was performed to identify eligible observational studies published from inception to July 17, 2020. The categorical and dose-response meta-analysis was conducted by pooling relative risk (RR) or odds ratio (OR) estimates with 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression and stratification analysis. Sensitivity analysis and publication bias test were also carried out.Results: Forty-five articles involving 475,579 individuals were included in the meta-analysis. Among the thirty-three studies on the association between breastfeeding and risk of childhood leukemia, the pooled risk estimates were 0.77 (95% CI, 0.65–0.91) and 0.77 (95% CI 0.63–0.94) for ever versus non/occasional breastfeeding and longest versus shortest breastfeeding duration group, respectively. There was clear indication for non-linear dose-response relationship between breastfeeding duration and the risk of childhood leukemia (Pnon-linear < 0.001). The most protective effect (OR, 0.66, 95% CI 0.62–0.70) was observed at a breastfeeding duration of 9.6 months. Four studies examined, the association between breastfeeding and risk of childhood neuroblastoma, and significant inverse associations were consistently observed in both the comparisons of ever breastfeeding versus non/occasional breastfeeding (OR = 0.59, 95% CI 0.44–0.81) and longest versus shortest breastfeeding (OR = 0.61, 95% CI 0.44–0.83). However, no associations of breastfeeding with risk of other cancers were found.Conclusions: Our study supports a protective role of breastfeeding on the risk of childhood leukemia, also suggesting a non-linear dose-response relationship. Further studies are warranted to confirm the association between breastfeeding and risk of childhood neuroblastoma.

Objective To quantify rheumatoid arthritis (RA) cases attributable to selected non-genetic risk factors. Design National Health and Nutrition Examination Survey (NHANES) and meta-analysis. Participants US adults. Data sources The prevalence of exposure was obtained from NHANES. Weighted analysis was performed to account for the complex sampling design in NHANES. PubMed and Web of Science up to 31 March 2019 were searched to identify epidemiological studies reported the association between non-genetic risk factors and RA in US adults. Relative risk (RR) value and the corresponding CI were pooled by meta-analysis to evaluate the associations between modifiable risk factors and RA. Population attributable fraction (PAF) was calculated based on the prevalence and RR data. Results The weighted percentages of former smokers, current smokers and overweight or obese people were 24.84%, 23.93% and 63.97%, and the average alcohol consumption was 51.34 g/week. In the meta-analysis, we found that former smokers (RR 1.22, 95% CI 1.10 to 1.36) and current smokers (RR 1.47, 95% CI 1.29 to 1.68) had higher risks of RA. Overweight and obese individuals had 1.27-fold (95% CI 1.09 to 1.48) increased risk of RA. Each per 50 g/week increment of alcohol consumption was associated with 8% (95% CI 0% to 16%) reduction in the risk of RA. Therefore, PAF value of smoking was 14.00% (95% CI 8.13% to 23.33%). Excess body mass index (BMI) was found to account for 14.73% (95% CI 5.45% to 23.50%) of RA incidence. The fraction of RA risk attributed by low alcohol intake was 8.21% (95% CI 0.31% to 16.39%). Collectively, we found that 32.69% (95% CI 13.41% to 50.96%) of RA cases were attributable to smoking, overweight or obesity and low alcohol drinking. Conclusion Nearly 33% of RA incidence was attributed to smoking, excess BMI and low alcohol drinking in USA. Our findings could provide a basis for developing guidelines of RA prevention and control in USA.

Background: Evidence from observational studies on the association of folate and vitamin B₁₂with autoimmune diseases are conflicting.Objective: We aimed to investigate the relationship of folate and vitamin B₁₂with autoimmune diseases using Mendelian randomization (MR).Materials and methods: We selected single-nucleotide polymorphisms associated with folate and vitamin B₁₂at the genome-wide significance level. Summary-level data for four common autoimmune diseases (vitiligo, inflammatory bowel disease, rheumatoid arthritis, and systemic lupus erythematosus) were obtained from large-scale genome-wide association studies, with a sample size of 44,266, 86,640, 58,284, and 23,210, respectively. MR analyses were conducted using the inverse variance weighted (IVW) approach, and sensitivity analyses were further performed to test the robustness.Results: We found that a higher genetically determined serum folate level per one standard deviation (SD) was associated with a decreased risk of vitiligo by the IVW method [odds ratios (OR) = 0.47; 95% confidence interval (CI): 0.32–0.69;P= 1.33 × 10^-4]. Sensitivity analyses using alternative methods showed similar associations, and no evidence of pleiotropy was detected by MR-Egger regression (P= 0.919). In addition, we observed that vitamin B₁₂per one SD was positively associated with IBD (IVW: OR = 1.14, 95% CI: 1.03–1.26,P= 0.010; maximum likelihood: OR = 1.14, 95% CI: 1.01–1.29,P= 0.035; MR-PRESSO: OR = 1.14, 95% CI:1.01–1.28,P=0.037), while the association was not significant after Bonferroni correction.Conclusion: The study provides convincing evidence for an inverse association between serum folate level and risk of vitiligo. Further studies are warranted to elucidate the possible association between vitamin B₁₂and risk of IBD.