Impact of lowering fine particulate matter from major emission sources on mortality in Canada: A nationwide causal analysis.

Emissions of fine particulate matter (PM2.5) from human activities have been linked to substantial disease burdens, but evidence regarding how reducing PM2.5 at its sources would improve public health is sparse. We followed a population-based cohort of 2.7 million adults across Canada from 2007 through 2016. For each participant, we estimated annual mean concentrations of PM2.5 and the fractional contributions to PM2.5 from the five leading anthropogenic sources at their residential address using satellite observations in combination with a global atmospheric chemistry transport model. For each source, we estimated the causal effects of six hypothetical interventions on 10-y nonaccidental mortality risk using the parametric g-formula, a structural causal model. We conducted stratified analyses by age, sex, and income. This cohort would have experienced tangible health gains had contributions to PM2.5 from any of the five sources been reduced. Compared with no intervention, a 10% annual reduction in PM2.5 contributions from transportation and power generation, Canada's largest and fifth-largest anthropogenic sources, would have prevented approximately 175 (95%CI: 123-226) and 90 (95%CI: 63-117) deaths per million by 2016, respectively. A more intensive 50% reduction per year in PM2.5 contributions from the two sources would have averted 360 and 185 deaths per million, respectively, by 2016. The potential health benefits were greater among men, older adults, and low-income earners. In Canada, where PM2.5 levels are among the lowest worldwide, reducing PM2.5 contributions from anthropogenic sources by as little as 10% annually would yield meaningful health gains.

Data-Driven Simulations to Assess the Impact of Study Imperfections in Time-to-Event Analyses.

Quantitative bias analysis (QBA) permits assessment of the expected impact of various imperfections of the available data on the results and conclusions of a particular real-world study. This article extends QBA methodology to multivariable time-to-event analyses with right-censored endpoints, possibly including time-varying exposures or covariates. The proposed approach employs data-driven simulations, which preserve important features of the data at hand while offering flexibility in controlling the parameters and assumptions that may affect the results. First, the steps required to perform data-driven simulations are described, and then two examples of real-world time-to-event analyses illustrate their implementation and the insights they may offer. The first example focuses on the omission of an important time-invariant predictor of the outcome in a prognostic study of cancer mortality, and permits separating the expected impact of confounding bias from non-collapsibility. The second example assesses how imprecise timing of an interval-censored event - ascertained only at sparse times of clinic visits - affects its estimated association with a time-varying drug exposure. The simulation results also provide a basis for comparing the performance of two alternative strategies for imputing the unknown event times in this setting. The R scripts that permit the reproduction of our examples are provided.

Differential Participation, a Potential Cause of Spurious Associations in Observational Cohorts in Environmental Epidemiology.

Differential participation in observational cohorts may lead to biased or even reversed estimates. In this article, we describe the potential for differential participation in cohorts studying the etiologic effects of long-term environmental exposures. Such cohorts are prone to differential participation because only those who survived until the start of follow-up and were healthy enough before enrollment will participate, and many environmental exposures are prevalent in the target population and connected to participation via factors such as geography or frailty. The relatively modest effect sizes of most environmental exposures also make any bias induced by differential participation particularly important to understand and account for. We discuss key points to consider for evaluating differential participation and use causal graphs to describe two example mechanisms through which differential participation can occur in health studies of long-term environmental exposures. We use a real-life example, the Canadian Community Health Survey cohort, to illustrate the non-negligible bias due to differential participation. We also demonstrate that implementing a simple washout period may reduce the bias and recover more valid results if the effect of interest is constant over time. Furthermore, we implement simulation scenarios to confirm the plausibility of the two mechanisms causing bias and the utility of the washout method. Since the existence of differential participation can be difficult to diagnose with traditional analytical approaches that calculate a summary effect estimate, we encourage researchers to systematically investigate the presence of time-varying effect estimates and potential spurious patterns (especially in initial periods in the setting of differential participation).

A Causal Mediation Analysis for Investigating the Effect of a Randomized Cash-Transfer Program in Nicaragua.

Mediation analysis can be applied to data from randomized trials of health and social interventions to draw causal inference concerning their mechanisms. We used data from a cluster-randomized trial in Nicaragua, fielded between 2000 and 2002, to investigate whether the impact of providing access to a conditional cash-transfer program on child nutritional outcomes was mediated by child health check-ups and household dietary diversity. In a sample of 443 children 6-35 months old, we estimated the controlled direct (CDE) effect of random assignment on measured height-for-age z scores had we intervened so that all children received a health check-up and had the same level of household dietary diversity, using inverse-probability weighted marginal structural models to account for mediator-outcome confounding. Sensitivity analyses corrected the CDE for potential nondifferential error in the measurement of dietary diversity. Treatment assignment increased height-for-age z score by 0.37 (95% CI: 0.05, 0.69) standard deviations. The CDE was 0.20 (95% CI: -0.17, 0.57) standard deviations, suggesting nearly one-half of the program's impact on child nutrition would be eliminated had we intervened on these factors, although estimates were relatively imprecise. This study provides an illustration of how causal mediation analysis can be applied to examine the mechanisms of multifaceted interventions.

Investigating the Shape and Strength of the Relationship Between Maternal Weight Gain and Gestational Age at Delivery in Twin and Singleton Pregnancies.

Both inadequate and excessive maternal weight gain are correlated with preterm delivery in singleton pregnancies, yet this relationship has not been adequately studied in twins. We investigated the relationship between time-varying maternal weight gain and gestational age at delivery in twin pregnancies and compared it with that in singletons delivered in the same study population. We used serial weight measurements abstracted from charts for twin and singleton pregnancies delivered during 1998-2013 in Pittsburgh, Pennsylvania. Our exposure was time-varying weight gain z score, calculated using gestational age-standardized and prepregnancy body mass index-stratified twin- and singleton-specific charts, and our outcome was gestational age at delivery. Our analyses used a flexible extension of the Cox proportional hazards model that allowed for nonlinear and time-dependent effects. We found a U-shaped relationship between weight gain z score and gestational age at delivery among twin pregnancies (lowest hazard of delivery observed at z score = 1.2), which we attributed to increased hazard of early preterm spontaneous delivery among pregnancies with low weight gain and increased hazard of late preterm delivery without labor among pregnancies with high weight gain. Our findings may be useful for updating provisional guidelines for maternal weight gain in twin pregnancies.

Mediation of the Effect of Incarceration on Selling Sex Among Black Sexual Minority Men and Black Transgender Women in the HPTN 061 Study.

Incarceration among Black sexual minority men and Black transgender women (BSMM/BTW) is disproportionately high in the United States. Limited research has documented the disruptive effect of incarceration on sexual networks and sexual partnership exchange among BSMM/BTW. We estimate the influence of incarceration on selling sex and mediating pathways among 1169 BSMM/BTW enrolled in the HIV Prevention Trials Network (HPTN) 061 cohort to assess this relationship. Mediators investigated were social support, violence, illicit drug use, and distress due to experienced racism and homophobia. During the 6 months following baseline, 14% of the cohort was incarcerated, including 24% of BTW. After adjustment, recent incarceration was associated with 1.57 (95% CI 1.02, 2.42) times the risk of subsequently selling sex. The hypothesized mediators together explained 25% of the relationship, with an indirect effect risk ratio of 1.09 (95% CI 0.97, 1.24). Our results document an association and call for more research investigating mechanisms.

Multilevel modelling for measuring interaction of effects between multiple categorical variables: An illustrative application using risk factors for preeclampsia.

BACKGROUND: Measuring multiple and higher-order interaction effects between multiple categorical variables proves challenging. OBJECTIVES: To illustrate a multilevel modelling approach to studying complex interactions. METHODS: We apply a two-level random-intercept linear regression to a binary outcome for individuals (level-1) nested within strata (level-2) defined by all observed combinations of multiple categorical exposure variables. As a pedagogic application, we analyse 36 strata defined by five risk factors of preeclampsia (parity, previous preeclampsia, chronic hypertension, multiple pregnancies, body mass index category) among 652,603 women in the Swedish Medical Birth Registry between 2002 and 2010. RESULTS: The absolute risk of preeclampsia was 4% but was predicted to vary from 1% to 44% across strata. The stratum discriminatory accuracy was 30% according to the variance partition coefficient (VPC) and 0.73 according to the area under the receiver operating characteristic curve (AUC). While the risk heterogeneity across strata was primarily due to the main effects of the categories defining the strata, 5% of the variation was attributable to their two- and higher-way interaction effects. One stratum presented a positive interaction, and two strata presented negative interaction. CONCLUSIONS: Multilevel modelling is an innovative tool for identifying and analysing higher-order interaction effects. Further work is needed to explore how this approach can best be applied to making causal inferences.

The burden of lower respiratory infections and their underlying etiologies in the Middle East and North Africa region, 1990-2019: results from the Global Burden of Disease Study 2019.

BACKGROUND: Lower respiratory infections (LRIs) cause substantial mortality and morbidity. The present study reported and analysed the burden of LRIs in the Middle East and North Africa (MENA) region between 1990 and 2019, by age, sex, etiology, and socio-demographic index (SDI). METHODS: The data used in this study were sourced from the Global Burden of Disease (GBD) study 2019. The annual incidence, deaths, and disability-adjusted life-years (DALYs) due to LRIs were presented as counts and age-standardised rates per 100,000 population, along with their 95% uncertainty intervals (UIs). The average annual percent changes (AAPC) in the age-standardised incidence, death and DALYs rates were calculated using Joinpoint software and correlations (Pearson's correlation coefficient) between the AAPCs and SDIs were calculated using Stata software. RESULTS: In 2019, there were 34.1 million (95% UI 31.7-36.8) incident cases of LRIs in MENA, with an age-standardised rate of 6510.2 (95% UI 6063.6-6997.8) per 100,000 population. The number of regional DALYs was 4.7 million (95% UI 3.9-5.4), with an age-standardised rate of 888.5 (95% UI 761.1-1019.9) per 100,000 population, which has decreased since 1990. Furthermore, Egypt [8150.8 (95% UI 7535.8-8783.5)] and Afghanistan [61.9 (95% UI 52.1-72.6)] had the highest age-standardised incidence and death rates, respectively. In 2019, the regional incidence and DALY rates were highest in the 1-4 age group, in both females and males. In terms of deaths, pneumococcus and H. influenza type B were the most and least common types of LRIs, respectively. From 1990 to 2019, the burden of LRIs generally decreased with increasing SDI. There were significant positive correlations between SDI and the AAPCs for the age-standardised incidence, death and DALY rates (p < 0.05). Over the 1990-2019 period, the regional incidence, deaths and DALYs attributable to LRIs decreased with AAPCs of - 1.19% (- 1.25 to - 1.13), - 2.47% (- 2.65 to - 2.28) and - 4.21% (- 4.43 to - 3.99), respectively. CONCLUSIONS: The LRI-associated burden in the MENA region decreased between 1990 and 2019. SDI had a significant positive correlation with the AAPC and pneumococcus was the most common underlying cause of LRIs. Afghanistan, Yemen and Egypt had the largest burdens in 2019. Further studies are needed to investigate the effectiveness of healthcare interventions and programs to control LRIs and their risk factors.

The burden of low back pain and its association with socio-demographic variables in the Middle East and North Africa region, 1990-2019.

BACKGROUND: Low back pain (LBP) is the most common musculoskeletal disorder globally. Providing region- and national-specific information on the burden of low back pain is critical for local healthcare policy makers. The present study aimed to report, compare, and contextualize the prevalence, incidence and years lived with disability (YLDs) of low back pain in the Middle East and North Africa (MENA) region by age, sex and sociodemographic index (SDI), from 1990 to 2019. METHODS: Publicly available data were obtained from the Global Burden of Disease (GBD) study 2019. The burden of LBP was reported for the 21 countries located in the MENA region, from 1990 to 2019. All estimates were reported as counts and age-standardised rates per 100,000 population, together with their corresponding 95% uncertainty intervals (UIs). RESULTS: In 2019, the age-standardised point prevalence and incidence rate per 100,000 in MENA were 7668.2 (95% UI 6798.0 to 8363.3) and 3215.9 (95%CI 2838.8 to 3638.3), which were 5.8% (4.3 to 7.4) and 4.4% (3.4 to 5.5) lower than in 1990, respectively. Furthermore, the regional age-standardised YLD rate in 2019 was 862.0 (605.5 to 1153.3) per 100,000, which was 6.0% (4.2 to 7.7) lower than in 1990. In 2019, Turkey [953.6 (671.3 to 1283.5)] and Lebanon [727.2 (511.5 to 966.0)] had the highest and lowest age-standardised YLD rates, respectively. There was no country in the MENA region that showed increases in the age-standardised prevalence, incidence or YLD rates of LBP over the measurement period. Furthermore, in 2019 the number of prevalent cases were highest in the 35-39 age group, with males having a higher number of cases in all age groups. In addition, the age-standardised YLD rates for males in the MENA region were higher than the global estimates in almost all age groups, in both 1990 and 2019. Furthermore, the burden of LBP was not associated with the level of socio-economic development during the measurement period. CONCLUSION: The burden attributable to LBP in the MENA region decreased slightly from 1990 to 2019. Furthermore, the burden among males was higher than the global average. Consequently, more integrated healthcare interventions are needed to more effectively alleviate the burden of low back pain in this region.

Structural determinants explain caries differences among preschool children in Chile's Metropolitan Region.

OBJECTIVE: To estimate the association between Social Determinants of Health (structural and intermediate) and caries indicators in Chile's Metropolitan Region preschool children. METHODS: A multilevel cross-sectional study of Social Determinants of Health (SDH) and caries in children aged 1 to 6 years in Chile's Metropolitan Region was conducted in 2014-2015, with three levels: district, school and child. Caries were assessed by the dmft-index and the prevalence of untreated caries. The structural determinants analyzed were Community Human Development Index (CHDI), urban/rural location, school type, caregiver's education and family income. Poisson multilevel regression models were fit. RESULTS: The sample size was 2,275 children from 40 schools in 13 districts. While the highest CHDI district had an untreated caries prevalence of 17.1% (12.3-22.7%), in the most disadvantaged district it was 53.9% (95% CI 46.0-61.6%). As family income increased, the probability of untreated caries prevalence decreased (PR = 0.9 95% CI 0.8-1.0). Rural districts had an average dmft-index of 7.3 (95% CI 7.2-7.4), while in urban districts, it was 4.4 (95% CI 4.3-4.5). Higher probabilities of untreated caries prevalence (PR = 3.0 95% CI 2.3-3.9) were observed in rural children. Greater probabilities of untreated caries prevalence (PR = 1.3 95% CI 1.1-1.6) and prevalence of caries experience (PR = 1.3 95% CI 1.1-1.5) were observed in children whose caregivers had a secondary educational level. CONCLUSIONS: A strong association was observed between the social determinants of health, specifically the structural ones, and the caries indicators studied in children of the Metropolitan Region of Chile. There were notable differences in caries between districts according to social advantage. Rurality and caregiver's education were the most consistent predictors.

Health care services use, stillbirth, and neonatal and infant survival following implementation of the Maternal Health Voucher Scheme in Bangladesh: A difference-in-differences analysis of Bangladesh Demographic and Health Survey data, 2000 to 2016.

BACKGROUND: Starting in 2006 to 2007, the Government of Bangladesh implemented the Maternal Health Voucher Scheme (MHVS). This program provides pregnant women with vouchers that can be exchanged for health services from eligible public and private sector providers. In this study, we examined whether access to the MHVS was associated with maternal health services utilization, stillbirth, and neonatal and infant mortality. METHODS AND FINDINGS: We used information on pregnancies and live births between 2000 to 2016 reported by women 15 to 49 years of age surveyed as part of the Bangladesh Demographic and Health Surveys. Our analytic sample included 23,275 pregnancies lasting at least 7 months for analyses of stillbirth and between 15,125 and 21,668 live births for analyses of health services use, neonatal, and infant mortality. With respect to live births occurring prior to the introduction of the MHVS, 31.3%, 14.1%, and 18.0% of women, respectively, reported receiving at least 3 antenatal care visits, delivering in a health institution, and having a skilled birth attendant at delivery. Rates of neonatal and infant mortality during this period were 40 and 63 per 1,000 live births, respectively, and there were 32 stillbirths per 1,000 pregnancies lasting at least 7 months. We applied a difference-in-differences design to estimate the effect of providing subdistrict-level access to the MHVS program, with inverse probability of treatment weights to address selection into the program. The introduction of the MHVS program was associated with a lagged improvement in the probability of delivering in a health facility, one of the primary targets of the program, although associations with other health services were less evident. After 6 years of access to the MHVS, the probabilities of reporting at least 3 antenatal care visits, delivering in a health facility, and having a skilled birth attendant present increased by 3.0 [95% confidence interval (95% CI) = -4.8, 10.7], 6.5 (95% CI = -0.6, 13.6), and 5.8 (95% CI = -1.8, 13.3) percentage points, respectively. We did not observe evidence consistent with the program improving health outcomes, with probabilities of stillbirth, neonatal mortality, and infant mortality decreasing by 0.7 (95% CI = -1.3, 2.6), 0.8 (95% CI = -1.7, 3.4), and 1.3 (95% CI = -2.5, 5.1) percentage points, respectively, after 6 years of access to the MHVS. The sample size was insufficient to detect smaller associations with adequate precision. Additionally, we cannot rule out the possibility of measurement error, although it was likely nondifferential by treatment group, or unmeasured confounding by concomitant interventions that were implemented differentially in treated and control areas. CONCLUSIONS: In this study, we found that the introduction of the MHVS was positively associated with the probability of delivering in a health facility, but despite a longer period of follow-up than most extant evaluations, we did not observe attendant reductions in stillbirth, neonatal mortality, or infant mortality. Further work and engagement with stakeholders is needed to assess if the MHVS has affected the quality of care and health inequalities and whether the design and eligibility of the program should be modified to improve maternal and neonatal health outcomes.

Increasing Representation of Epidemiologists From Around the World in the Society for Epidemiologic Research: The Case of Mexico.

Mexico has a population of 129 million and is considered one of the most unequal countries in the world, suffering from widespread health disparities. There is a pressing need to strengthen epidemiologic capacity in Mexico, to help solve the complex health problems the country faces and to reduce health inequities. However, the representation of Mexican epidemiologists in the largest epidemiologic society in North America is low, despite the short distance to the United States. In this commentary, we discuss the barriers to higher representation of Mexican epidemiologists within the Society for Epidemiologic Research (SER), including language barriers, costs, and regional necessities. We also discuss opportunities to expand Mexican SER representation and collaboration. Overall, we hope that this is a call towards expanding SER global participation and starting a conversation on a common agenda for epidemiologic research.

Global, regional, and national cancer deaths and disability-adjusted life-years (DALYs) attributable to alcohol consumption in 204 countries and territories, 1990-2019.

BACKGROUND: Alcohol consumption is a risk factor for a number of communicable and non-communicable diseases, including several types of cancer. This article reports the burden of cancers attributable to alcohol consumption by age, sex, location, sociodemographic index (SDI), and cancer type from 1990 to 2019. METHODS: The Comparative Risk Assessment approach was used in the 2019 Global Burden of Disease study to report the burden of cancers attributable to alcohol consumption between 1990 and 2019. RESULTS: In 2019, there were globally an estimated 494.7 thousand cancer deaths (95% uncertainty interval [UI], 439.7 to 554.1) and 13.0 million cancer disability-adjusted life-years (DALYs; 95% UI, 11.6 to 14.5) that were attributable to alcohol consumption. The alcohol-attributable DALYs were much higher in men (10.5 million; 95% UI, 9.2 to 11.8) than women (2.5 million; 95% UI, 2.2 to 2.9). The global age-standardized death and DALY rates of cancers attributable to alcohol decreased by 14.7% (95% UI, 6.4% to 23%) and 18.1% (95% UI, 9.2% to 26.5%), respectively, over the study period. Central Europe had the highest age-standardized death rates that were attributable to alcohol consumption(10.3; 95% UI, 8.7 to12.0). Moreover, there was an overall positive association between SDI and the regional age-standardized DALY rate for alcohol-attributable cancers. CONCLUSIONS: Despite decreases in age-standardized deaths and DALYs, substantial numbers of cancer deaths and DALYs are still attributable to alcohol consumption. Because there is a higher burden in males, the elderly, and developed regions (based on SDI), these groups and regions should be prioritized in any prevention programs.

Gestational Diabetes in Twin Versus Singleton Pregnancies With Normal Weight or Overweight Pre-Pregnancy Body Mass Index: The Mediating Role of Mid-Pregnancy Weight Gain.

BACKGROUND: Gestational diabetes might be more common in twin versus singleton pregnancies, yet the reasons for this are unclear. We evaluated the extent to which this relationship is explained by higher mid-pregnancy weight gain within normal weight and overweight pre-pregnancy body mass index (BMI) strata. METHODS: We analyzed serial weights and glucose screening and diagnostic data abstracted from medical charts for twin (n = 1397) and singleton (n = 3117) pregnancies with normal or overweight pre-pregnancy BMI delivered from 1998 to 2013 at Magee-Womens Hospital in Pennsylvania. We used causal mediation analyses to estimate the total effect of twin versus singleton pregnancy on gestational diabetes, as well as those mediated (natural indirect effect) and not mediated (natural and controlled direct effects) by pathways involving mid-pregnancy weight gain. RESULTS: Odds of gestational diabetes were higher among twin pregnancies [odds ratios (ORs) for total effect = 2.83 (95% CI = 1.54, 5.19) for normal weight and 2.09 (95% CI = 1.16, 3.75) for overweight pre pregnancy BMI], yet there was limited evidence that this relationship was mediated by mid-pregnancy weight gain [ORs for natural indirect effect = 1.21 (95% CI = 0.90, 1.24) for normal weight and 1.06 (95% CI = 0.92, 1.21) for overweight pre-pregnancy BMI] and more evidence of mediation via other pathways [ORs for natural direct effect = 2.34 (95% CI = 1.24, 4.40) for normal weight and 1.97 (95% CI = 1.08, 3.60) for overweight pre-pregnancy BMI]. CONCLUSIONS: While twin pregnancies with normal weight or overweight pre-pregnancy BMI experienced higher odds of gestational diabetes versus singletons, most of this effect was explained by pathways not involving mid-pregnancy weight gain.

Incarceration and Sexual Risk Behavior and Incident Sexually Transmitted Infection/HIV in HIV Prevention Trials Network 061: Differences by Study City and Among Black Sexual Minority Men Who Have Sex With Men, Black Sexual Minority Men Who Have Sex With Men and Women, and Black Transgender Women.

BACKGROUND: Black sexual minority men (BSMM) and Black transgender women face a disproportionate risk of incarceration and sexually transmitted infection (STI)/HIV, yet research on the longitudinal association between incarceration and STI/HIV risk in these groups is limited. METHODS: We used data from the HIV Prevention Trials Network (HPTN) 061 study conducted among BSMM and Black transgender women in Atlanta, Boston, Los Angeles, New York City, San Francisco, and Washington, DC, restricting analyses to those who returned for the 6-month follow-up visit when recent incarceration was measured (n = 1169). Using inverse probability of treatment weighting, we measured associations between incarceration and next 6-month multiple partnerships; selling or buying sex; condomless anal intercourse; and incident chlamydia, gonorrhea, syphilis, and HIV. We explored differences by study city, and among BSMM who had sex with men only, BSMM who had sex with men and women, and Black transgender women. RESULTS: Approximately 14% reported past 6-month incarceration. Incarceration was associated with next 6-month selling sex (adjusted risk ratio [ARR], 1.80; 95% confidence interval [CI], 1.12-2.87) in the overall sample and multiple partnerships among BSMM who had sex with men and women (ARR, 1.34; 95% CI, 1.10-1.63) and transgender women (ARR, 1.77; 95% CI, 1.22-2.57). There is evidence suggesting that incarceration may predict gonorrhea (ARR, 2.35; 95% CI, 0.95-5.77), with particularly strong associations observed in Los Angeles (ARR, 6.48; 95% CI, 1.48-28.38). CONCLUSIONS: Incarceration may increase STI/HIV risk among BSMM and Black transgender women. Additional mixed-methods research is needed to validate associations and understand pathways.

Association between long-term exposure to ambient air pollution and COVID-19 severity: a prospective cohort study.

BACKGROUND: The tremendous global health burden related to COVID-19 means that identifying determinants of COVID-19 severity is important for prevention and intervention. We aimed to explore long-term exposure to ambient air pollution as a potential contributor to COVID-19 severity, given its known impact on the respiratory system. METHODS: We used a cohort of all people with confirmed SARS-CoV-2 infection, aged 20 years and older and not residing in a long-term care facility in Ontario, Canada, during 2020. We evaluated the association between long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2) and ground-level ozone (O3), and risk of COVID-19-related hospital admission, intensive care unit (ICU) admission and death. We ascertained individuals' long-term exposures to each air pollutant based on their residence from 2015 to 2019. We used logistic regression and adjusted for confounders and selection bias using various individual and contextual covariates obtained through data linkage. RESULTS: Among the 151 105 people with confirmed SARS-CoV-2 infection in Ontario in 2020, we observed 8630 hospital admissions, 1912 ICU admissions and 2137 deaths related to COVID-19. For each interquartile range increase in exposure to PM2.5 (1.70 µg/m3), we estimated odds ratios of 1.06 (95% confidence interval [CI] 1.01-1.12), 1.09 (95% CI 0.98-1.21) and 1.00 (95% CI 0.90-1.11) for hospital admission, ICU admission and death, respectively. Estimates were smaller for NO2. We also estimated odds ratios of 1.15 (95% CI 1.06-1.23), 1.30 (95% CI 1.12-1.50) and 1.18 (95% CI 1.02-1.36) per interquartile range increase of 5.14 ppb in O3 for hospital admission, ICU admission and death, respectively. INTERPRETATION: Chronic exposure to air pollution may contribute to severe outcomes after SARS-CoV-2 infection, particularly exposure to O3.

Differences in birthweight by maternal and paternal nativity status in Canada.

BACKGROUND: Parental nativity, as well as duration of residence of foreign-born parents in the host country, has been shown to be associated with size at birth. However, most studies have focused on maternal nativity status only and have not accounted for important characteristics of both parents. OBJECTIVE: To explore whether maternal and paternal nativity and length of residence (LOR) are independently associated with birthweight for gestational age in a representative sample of infants in Canada. METHODS: We compared mean differences in sex- and gestational age-standardised birthweight z-score by nativity status of both parents in a nationally representative sample of 130,532 singleton infants born between May 2004 and May 2006 to mothers residing in Canada. We categorised parental nativity status into four groups (both parents Canada-born, mother only foreign-born, father only foreign-born and both parents foreign-born) and parents' LOR into three (both ≤10 years, only one parent ≤10 years and both >10 years). We estimated mean differences in birthweight z-score and their 95% confidence intervals in linear regression models adjusted for parity, parents' ages, education, ethnicity and marital status of the mother. RESULTS: Compared with babies of Canada-born couples, those of two foreign-born parents had on average smaller birthweight z-score, -0.23 (95% CI -0.28, -0.25). However, after adjustment, the mean difference in z-score was -0.02 (95% CI -0.05, 0.00). Infants born to parents who had both resided in Canada for ≤10 years had a unadjusted mean difference in z-score of -0.27 (95% CI -0.29, -0.26), compared infants whose parents were both Canada-born, but the difference became negligible (-0.02, 95% CI -0.04, 0.01) after adjustment. CONCLUSION: The birthweight differences by parental nativity or length of residence observed in our study population could be attributed to differences in the distribution of other parental characteristics that affect birthweight.

Burden of tension-type headache in the Middle East and North Africa region, 1990-2019.

INTRODUCTION: Tension-type headache (TTH) is the most prevalent neurological disorder. As there is a gap in the literature regarding the disease burden attributable to TTH in the Middle East and North Africa (MENA) region, the aim of the present study was to report the epidemiological indicators of TTH in MENA, from 1990 to 2019, by sex, age and socio-demographic index (SDI). METHODS: Publicly available data on the point prevalence, annual incidence and years lived with disability (YLDs) were retrieved from the global burden of disease (GBD) 2019 study for the 21 countries and territories in MENA, between 1990 and 2019. The results were presented with numbers and age-standardised rates per 100000 population, along with their corresponding 95% uncertainty intervals (UIs). RESULTS: In 2019, the age-standardised point prevalence and annual incidence rates for TTH in the MENA region were 24504.5 and 8680.1 per 100000, respectively, which represents a 2.0% and a 0.9% increase over 1990-2019, respectively. The age-standardised YLD rate of TTH in this region in 2019 was estimated to be 68.1 per 100000 population, which has increased 1.0% since 1990. Iran [29640.4] had the highest age-standardised point prevalence rate for TTH, while Turkey [21726.3] had the lowest. In 2019, the regional point prevalence of TTH was highest in the 35-39 and 70-74 age groups, for males and females, respectively. Furthermore, the number of prevalent cases was estimated to be highest in those aged 35-39 and 25-29 years, in both males and females, respectively. Moreover, the burden of TTH was not observed to have a clear association with SDI. CONCLUSIONS: While the prevalence of TTH in the MENA region increased from 1990 to 2019, the incidence rate did not change. In addition, the burden of TTH in MENA was higher than at the global level for both sexes and all age groups. Therefore, prevention of TTH would help alleviate the attributable burden imposed on the hundreds of millions of people suffering from TTH around the region.

Invited Commentary: The Society for Epidemiologic Research's Commitment to Diversity and Equity-Pathways to Filling the Glass.

In the article by Nobles et al. (Am J Epidemiol. 2021;190(9):1710-1720), characteristics of those epidemiologists selected for various chair and presentation roles at the annual meetings of the Society for Epidemiologic Research (SER) from 2015 through 2017 were examined. Characteristics that were compared included inferred gender, institutional affiliation, subject area, and h-index. Important disparities were observed between session chairs, speakers, and poster presenters. SER leadership considers diversity and equity to be priorities and is committed to positive change. New programs and processes have been used to broaden participation and improve diversity since 2018, but the SER must continue its efforts to change processes and monitor of the experiences of SER members. A diversity of perspectives within the SER membership and at its meetings will improve all aspects of our practice of epidemiology.

Use of Racial and Ethnic Categories in Medical Testing and Diagnosis: Primum Non Nocere.

BACKGROUND: Use of race and ethnicity is common in medical tests and procedures, even though these categories are defined by sociological, historical, and political processes, and vary considerably in their definitions over time and place. Because all societies organize themselves around these constructs in some way, they are undeniable facets of the human experience, with myriad health consequences. In the biomedical literature, they are also commonly interpreted as representing biological heterogeneity that is relevant for health and disease. CONTENT: We review the use of race and ethnicity in medical practice, especially in the USA, and provide 2 specific examples to represent a large number of similar instances. We then critique these uses along a number of different dimensions, including limitations in measurement, within- versus between-group variance, and implications for informativeness of risk markers for individuals, generalization from arbitrary or nonrepresentative samples, perpetuation of myths and stereotypes, instability in time and place, crowding out of more relevant risk markers, stigmatization, and the tainting of medicine with the history of oppression. We conclude with recommendations to improve practice that are technical, ethical, and pragmatic. SUMMARY: Medicine has evolved from a mystical healing art to a mature science of human health through a rigorous process of quantification, experimentation, and evaluation. Folkloric traditions, such as race- and ethnic-specific medicine will fade from use as we become increasingly critical of outdated and irrational clinical practices and replace these with personalized, evidenced-based tests, algorithms, and procedures that privilege patients' individual humanity over obsolete and misleading labels.