The evolution of workplace risk for Covid-19 in Canadian healthcare workers and its relation to vaccination: A nested case-referent study.

BACKGROUND: During the early months of the Covid-19 pandemic, studies demonstrated that healthcare workers (HCWs) were at increased risk of infection. Few modifiable risks were identified. It is largely unknown how these evolved over time. METHODS: A prospective case-referent study was established and nested within a cohort study of Canadian HCWs. Cases of Covid-19, confirmed by polymerase chain reaction, were matched with up to four referents on job, province, gender, and date of first vaccination. Cases and referents completed a questionnaire reporting exposures and experiences in the 21 days before case date. Participants were recruited from October 2020 to March 2022. Workplace factors were examined by mixed-effects logistic regression allowing for competing exposures. A sensitivity analysis was limited to those for whom family/community transmission seemed unlikely. RESULTS: 533 cases were matched with 1697 referents. Among unvaccinated HCWs, the risk of infection was increased if they worked hands-on with patients with Covid-19, on a ward designated for care of infected patients, or handled objects used by infected patients. Sensitivity analysis identified work in residential institutions and geriatric wards as high risk for unvaccinated HCWs. Later, with almost universal HCW vaccination, risk from working with infected patients was much reduced but cases were more likely than referents to report being unable to access an N95 mask or that decontaminated N95 masks were reused. CONCLUSIONS: These results suggest that, after a rocky start, the risks of Covid-19 infection from work in health care are now largely contained in Canada but with need for continued vigilance.

Ergonomic demands and fetal loss in women in welding and electrical trades: A Canadian cohort study.

OBJECTIVES: To determine the relationship between ergonomic demands of the job at conception and fetal loss (miscarriage or stillbirth). METHODS: Women with a welding or electrical trade apprenticeship were identified across Canada for the Women's Health in Apprenticeship Trades-Metal and Electrical study. They completed a reproductive and employment history at recruitment and every 6 months for up to 5 years to provide details on pregnancies and work demands. Job at conception was identified and fetal loss examined in relation to ergonomic exposures/demands, allowing for potential confounders. RESULTS: A total of 885 women were recruited; 447 in welding and 438 in electrical trades. Of these, 574 reported at least one pregnancy. Analysis of 756 pregnancies since the woman started in her trade suggested no increased risk of fetal loss in those choosing welding rather than electrical work. Among 506 pregnancies conceived during a period working in a trade, 148 (29.2%) ended in fetal loss: 31.2% (73/234) in welding, and 27.6% (75/272) in electrical work. Detailed exposure information was available for 59% (299/506) of these pregnancies. In welders, the risk of fetal loss was increased with whole-body vibration (prevalence ratio [PR] = 2.14; 95% confidence interval [CI] 1.39-3.31) and hand-arm vibration for > 1 hour/day (PR = 2.15; 95% CI 1.33-3.49). In electrical workers risk increased with more than 8 days working without a rest day (PR = 2.29; 95% CI 1.25-4.17). Local exhaust ventilation reduced risk in welders. CONCLUSIONS: There was no significant increase in fetal loss in welding trades compared to electrical work. Vibration, largely from grinding, and extended work rotations appear to be potentially modifiable factors of some importance.

Prevalence of Mental Ill-Health in a Cohort of First Responders Attending the Fort McMurray Fire.

OBJECTIVES: The study was designed to estimate the prevalence of mental disorders in a cohort of firefighters who had been deployed to a devastating fire in Fort McMurray, Alberta, in 2016. METHODS: A cohort of firefighters was established and followed up by online questionnaires. The contact in October 2018 to March 2019 included the PCL-5 questionnaire screening for post-traumatic stress disorder (PTSD) and the Hospital Anxiety and Depression Scale (HADS) screening for anxiety and depression. A sample was selected comprising all scoring ≥31 on the PCL-5 or ≥12 on either scale of the HADS, 30% of those scoring 8 to 11 on the HADS, and 10% of those with lower scores on all scales. This sample was assessed through a structured clinical interview to categorize disorders as defined in Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5). Interviews were carried out face-to-face or by telephone between August 2019 and February 2020. Diagnoses in the interview sample were reweighted to obtain prevalence estimates for the whole cohort. In an analysis of receiver operating characteristics (ROC), possible cut points for scores from each screening questionnaire were examined. RESULTS: In 2018 to 2019, 1,000 of the cohort of 1,234 firefighters completed the HADS and 998 completed the PCL-5. Of these, 282 were identified for structured clinical interviews for DSM-5 (SCID) assessment. Interviews were carried out with 192. Among those assessed, 40.6% met the criteria for PTSD, 30.7% for an anxiety disorder, and 28.5% for a depressive disorder. When reweighted to allow for sampling and losses to assessment, cohort prevalence estimates were as follows: PTSD 21.4% (15.7% to 29.1%), anxiety disorders 15.8% (11.0% to 22.5%), and depressive disorders 14.3% (9.9% to 20.8%). Lower prevalence estimates were obtained when using the cut point with least misclassification in the ROC analysis. CONCLUSION: Using the gold-standard SCID assessment, high rates of mental disorders were found in this cohort of firefighters who had experienced a devastating fire. Fewer cases would have been identified by screening questionnaire alone.

The role of organizational supports in mitigating mental ill health in firefighters: A cohort study in Alberta, Canada.

INTRODUCTION: Little is known about the effectiveness of ongoing mental health support in reducing the mental health impacts of a traumatic deployment. METHODS: A cohort of firefighters was established among those deployed to a devastating wildfire in Alberta, Canada in May 2016. Firefighters completed three questionnaires: at recruitment giving details of exposures, a first follow-up reporting mental health supports before, during, and after the fire and a second follow-up, at least 30 months after the fire, with screening questionnaires for anxiety, depression, and posttraumatic stress disorder (PTSD). Fire chiefs were interviewed about mental health provisions. The impact of supports on mental ill health was estimated, adjusting for clustering within fire service and potential confounders. RESULTS: Of 1234 firefighters in the cohort, 840 completed the questionnaire on mental health supports. In total, 78 of 82 fire chiefs were interviewed. Analysis of the impact of supports on mental ill health included 745 firefighters from 67 fire services. Only 45.8% of reports of peer support were concordant between firefighters and fire chiefs. After adjusting for confounding, the odds ratios (OR) for peer support reported by both fire chief and firefighter were depressive disorder: OR = 0.22, 95% confidence interval (CI), 0.08-0.61; anxiety disorder: OR = 0.45, 95% CI, 0.24-0.82; PTSD: OR = 0.62, 95% CI, 0.37-1.02. Symptoms of anxiety and depression but not PTSD were reduced by resiliency training before the fire and by support offered within 48 h of return from deployment. CONCLUSION: The results suggest peer support in firefighters is protective but its availability is poorly recognized. PTSD was somewhat less responsive, perhaps reflecting the cumulative effects of previous exposures.

Promoting and maintaining urinary continence: Follow-up from a cluster-randomized trial of elderly village women in Bangladesh.

AIMS: Pelvic floor and mobility exercises were shown to be effective in managing incontinence in a cluster-randomized trial (CRT) of village women aged 60 to 75 years in Bangladesh. The present analysis examines continence 12 months after the CRT and exercise program implementation with village paramedics as preceptors. METHODS: Women from nine villages in the exercise arm of the CRT were followed-up 12 months after the 6-month intervention. They provided information about exercise since the CRT and a 3-day continence record (3DCR). Posttrial, a further 6-month exercise intervention led by village paramedics was initiated in 20 villages. Women completed the two-item Sandvik severity questionnaire before and after the intervention. Paramedics kept a record of each woman's attendance at the 48 exercise sessions RESULTS: A total of 130 of 150 women from the CRT completed the 12-month follow-up; 61.5% were dry on the 3DCR at follow-up. Total continence was related to the continuation of exercises carried out in the home and absence of urinary tract infection at follow-up. Those exercising at follow-up had an odds ratio (OR) of 3.49 (95% confidence interval [CI], 1.86-6.58) of being continent at follow-up. Higher end-of-CRT body mass index was associated with greater follow-up leakage. In the 20-village roll-out, with 316 incontinent women, improvement in both severity and total continence on the Sandvik questionnaire were related to a total number of sessions attended (OR = 1.09; 95% CI, 1.05-1.13). At roll-out, 38.6% achieved continence, comparable to 43.0% in the CRT using physiotherapy preceptors CONCLUSIONS: Group exercise classes led by paramedics resulted in a marked improvement in continence but maintenance requires exercise postintervention.

Total disability days in interprovincial and home-province workers injured in Alberta, Canada: A mixed-methods study with matched-pair analysis of compensation data and participant interviews.

INTRODUCTION: Workers moving between states or provinces to find employment are reported to take longer to return to work after the injury. METHODS: The Alberta Workers Compensation Board (WCB) identified all workers from four Canadian Atlantic provinces who sustained a work injury in Alberta resulting in greater than 5 total temporary disability days (TTDDays) from January 2015 to June 2017. Each was matched on sex, age, and injury date with an Alberta claimant also with greater than 5 TTDDays. WCB information extracted included employment, injury, cost and place of treatment, and modified work. Cox regression identified factors associated with TTDDays. Semi-structured interviews were also undertaken. RESULTS: Two-hundred forty pairs were identified and 60 interviews completed. Those from the Atlantic provinces had more TTDDays (median 63 days) than Alberta (median 22 days) with an unadjusted hazard ratio (HR) 0.50 (95% confidence interval [CI], 0.42-0.61). When adjusted for all factors, the HR moved closer to unity (HR = 0.62; 95% CI, 0.50-0.76). Total health care costs were the strongest predictor, with modified work, injury type, and claim status also explanatory factors. Among the Atlantic workers, leaving Alberta for treatment was strongly related to a lower likelihood of ending wage replacement (HR = 0.45; 95% CI, 0.32-0.62). Participants in the interview study emphasized the importance of returning to the family after injury and the financial difficulties of maintaining a second home with reduced income after the injury. CONCLUSION: The higher costs of wage replacement associated with extended time off work may be inherent to the practice of employing out-of-province workers for jobs for which there is a shortage of local labor.

Urinary hydroxypyrene determination for biomonitoring of firefighters deployed at the Fort McMurray wildfire: an inter-laboratory method comparison.

Urinary 1-hydroxypyrene (OH-Pyr) is widely used for biomonitoring human exposures to polycyclic aromatic hydrocarbons (PAHs) from air pollution and tobacco smoke. However, there have been few rigorous validation studies reported to ensure reliable OH-Pyr determination for occupational health and risk assessment. Herein, we report an inter-laboratory method comparison for urinary OH-Pyr when using gas chromatography-high-resolution mass spectrometry (GC-HRMS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) on urine specimens collected from firefighters (n = 42) deployed at the 2016 Fort McMurray wildfire. Overall, there was good mutual agreement in urinary OH-Pyr quantification following enzyme deconjugation with an average bias of 39% with no significant deviation from linearity (slope = 1.36; p > 0.05), whereas technical precision (< 12%) and average recovery (> 85%) were acceptable when using a stable-isotope internal standard. Faster analysis times (4 min) were achieved by LC-MS/MS without chemical derivatization, whereas lower detection limits (0.64 ng/L, S/N = 3) was realized with solid-phase extraction prior to GC-HRMS. A median creatinine normalized OH-Pyr concentration of 128 ng/g was measured for firefighters that were below the recommended biological exposure index due to delays between early stages of emergency firefighting and urine sample collection. Similar outcomes were also measured for 3-hydroxyphenanthrene and 9-hydroxyfluorene that were positively correlated with urinary OH-Pyr (p < 0.05), implying similar uptake, distribution, and liver biotransformation processes. Optimal specimen collection strategies post-deployment together with standardized protocols for OH-PAH analysis are critical to accurately evaluate smoke exposure in firefighters, including experimental conditions to ensure quantitative enzyme hydrolysis of urine samples. Graphical abstract.

Work injuries in internal migrants to Alberta, Canada. Do workers' compensation records provide an unbiased estimate of risk?

INTRODUCTION: It is not known whether out-of-province Canadians, who travel to Alberta for work, are at increased risk of occupational injury. METHODS: Workers' compensation board (WCB) claims in 2013 to 2015 for those injured in Alberta were extracted by home province. Denominator data, from Statistics Canada, indicated the numbers from Alberta and Newfoundland and Labrador (NL) employed in Alberta in 2012. Both datasets were stratified by industry, age, and gender. Logistic regression estimated the risk of a worker from NL making a WCB claim in 2013 or 2014, stratified by time lost from work. Bias from under-reporting was examined in responses to injury questions in a cohort of trades' workers across Canada and in a pilot study in Fort McMurray, Alberta. RESULTS: Injury reporting rate in workers from NL was lower than those from Alberta, with a marked deficit (odds ratio [OR] = 0.17; 95% confidence interval [CI], 0.12-0.27) for injuries resulting in 1 to 30 days off work. Among the 1520 from Alberta in the trades' cohort, 327 participants reported 444 work injuries: 34.5% were reported to the WCB, rising to 69.4% in those treated by a physician. A total of 52 injuries in Alberta were recorded by 151 workers in the Fort McMurray cohort. In logistic regression, very similar factors predicted WCB reporting in the trades and Fort McMurray cohorts, but those from out-of-province or recently settled in Alberta were much less likely to report (OR = 0.02; 95% CI, 0.00-0.40). CONCLUSION: Differential rates of under-reporting explain in part the overall low estimates of injuries in interprovincial workers but not the deficit in time-loss 1 to 30 days.

Social, obstetric and environmental determinants of low Apgar score among infants born in four selected hospitals in Ibadan, Nigeria.

Little information exists about socio-economic, environmental or occupational determinants of low Apgar scores among Nigerian neonates. Mothers in lying-in wards of four hospitals in Ibadan were interviewed on socio-demographic characteristics, obstetric history and work activities during index pregnancy. Apgar scores and clinical data were extracted from case notes. Of the 1349 respondents, 20% had Apgar score <7 at one minute, 4% at five minutes. Lower education, cooking with kerosene, physical exertion at work, nulliparity, hypertension in pregnancy, prolonged rupture of membranes, breech presentation and caesarean section were predictors for low Apgar scores at one minute; nulliparity, male infant and breech presentation at five minutes. Occupations with lower socio-economic status or those requiring physical exertion; tailoring, catering and hairdressing recorded higher rates of low Apgar scores at one minute (p = .08). Physical exertion at work and cooking with kerosene may be predictive of low Apgar scores and require further study.

Evaluation of the impact of a chronic disease scheme reimbursing medical costs of patients with diabetes in Anhui province, China: a follow-up study.

BACKGROUND: Although many studies have investigated the relationship between the introduction of the New Cooperative Medical Scheme (NCMS) in rural China in 2003 and increased use of medical services, the effect on health status, objectively measured, is seldom reported. In Anhui Province a chronic disease scheme (CDS) for reimbursing part of the cost of outpatient care is designed to improve management of those with chronic conditions, including diabetes. METHODS: A follow-up study was designed in which patients with diabetes aged 40-70 years who had recently (in 2010) been granted a chronic disease card were individually matched on age, sex and village with a patient with diabetes not yet in the scheme. Each subject gave a fingertip sample of blood to give the concentration of glycosylated hemoglobin (HbA1c), a measure indicating blood glucose control during the previous 3 months. This measure was made on recruitment and at 12 month follow-up: information on use of health services, quality of life and financial burden was also collected at the two contacts. RESULTS: Of 602 pairs initially recruited, 528 pairs were contacted at follow-up and are the subject of this report. To distinguish between outcomes associated with application and those of membership of the scheme, the primary analysis was of 256 pairs in which one had been a member of the CDS throughout and the other never applied. No difference between pairs on HbA1c was found either at recruitment or follow-up but those in the CDS reported more hospital visits, more tests and more use of high level hospitals. However they had poorer scores on quality of life scales (SF-12, EQ-5D) and were more likely to report that the financial costs were very burdensome. Those recently applying for the scheme, or being accepted since recruitment, had lower HbA1c scores. CONCLUSIONS: On-going membership of the CDS was associated with increased use of services but this did not appear to result in better management of blood glucose or improved quality of life. Those who had recently joined the scheme had signs of improvement, suggesting a need for active follow-up to maintain and reinforce early gains.

Genetic susceptibility to beryllium: a case-referent study of men and women of working age with sarcoidosis or other chronic lung disease.

OBJECTIVE: The study was designed to investigate whether beryllium exposure was related to illness diagnosed as sarcoidosis. Chronic beryllium disease (CBD) and sarcoidosis are clinically and pathologically indistinguishable, with only the presence of beryllium-specific T-lymphocytes identifying CBD. Testing for such cells is not feasible in community studies of sarcoidosis but a second characteristic of CBD, its much greater incidence in those with a glutamic acid residue at position 69 of the HLA-DPB1 gene (Glu69), provides an alternative approach to answering this question. METHODS: Cases of sarcoidosis aged 18-60 years diagnosed in Alberta, Canada, from 1999 to 2005 were approached through their specialist physician, together with age-matched and sex-matched referents with other chronic lung disease. Referents were grouped into chronic obstructive pulmonary disease (COPD), asthma and other lung disease. Participants completed a telephone questionnaire, including industry-specific questionnaires. DNA was extracted from mailed-in mouthwash samples and genotyped for Glu69. Duration of employment in types of work with independently documented beryllium exposure was calculated. RESULTS: DNA was extracted for 655 cases (270 Glu69 positive) and 1382 referents (561 positive). No increase in sarcoidosis was seen with either Glu69 or beryllium exposure (none, <10, ≥10 years) as main effects: longer duration in possible beryllium jobs was related to COPD. In Glu69 positive men with exposure ≥10 years, the trend towards increasing rate of COPD was reversed, and a significant interaction of duration of exposure and Glu69 was detected (OR=4.51 95% CI 1.17 to 17.48). CONCLUSIONS: The gene-environment interaction supports the hypothesis that some cases diagnosed as sarcoidosis result from occupational beryllium exposure.

Urinary metal concentrations among female welders.

As part of a Canada-wide study of women entering non-traditional trades [Women's Health in Apprenticeship Trades-Metalworkers and Electricians (WHAT-ME)], we examined spot urine samples from women welders in Alberta to determine whether urinary metal concentrations exceeded those of the general population, to compare levels to previously published urinary concentrations in male welders and to examine the relationship with welding tasks. Women mailed-in urine samples collected close to the time of completing a detailed exposure questionnaire, including welding tasks on their most recent day welding at work. Of 53 welders working in their trade, 45 had urinary creatinine >0.3-≤3.0g l(-1) and were included in analyses. Seven metals were examined for which both population and male welder urinary concentrations were available: cadmium, chromium, cobalt, copper, manganese, nickel, and zinc. Principal component analysis was used to extract three components from natural log transformed creatinine-corrected metal concentrations. Of the 45 women, 17 reported more than one main task. Overall two thirds worked in fabrication, a third on pipe welding, and smaller numbers on repair, in construction or other tasks: manual metal arc welding was reported by 62%, semi-automatic arc welding by 47%, and arc welding with a tungsten electrode by 15%. In multiple regression analyses, little relation was found between urinary metals and task or type of welding, except for cadmium where lower levels were seen in those reporting semi-automatic manual welding (after adjustment for age and smoking). The proportion of women welders exceeding the selected general population 95th percentile was high for manganese (96%) and chromium (29%). Urinary metal concentrations were similar to those reported for male welders with only manganese, with a geometric mean in women of 1.91 µg g(-1) creatinine, and perhaps copper (11.8 µg g(-1) creatinine), consistently lower in male welders. Although not evident from the task analysis reported here, differences in exposure by sex may be explained by type of welding or by other work practices. A closely comparable cohort of male welders would be necessary to examine this hypothesis more fully.

Occupation exposures and sperm morphology: a case-referent analysis of a multi-centre study.

OBJECTIVE: We examined occupational exposures and sperm morphology to establish whether exposures implicated differed from those affecting motile sperm concentration. METHODS: Computer aided sperm morphometric assessment was undertaken on morphology slides obtained as part of a multi-centre study in 1999-2002 of occupational factors in male infertility. Men attending 14 fertility clinics across the UK were recruited and gave a semen sample. Before results of the semen analysis were known, the men completed detailed questionnaires about their employment and lifestyle. Occupational exposures were assessed by occupational hygienists. Data were analysed using an unmatched case-referent design, allowing for clustering and for confounders. Three case definitions were used: poor morphology (normal morphology <4%), low motile sperm count (MSC) (<4.8×10(6)) and either condition. RESULTS: Morphology results were available for 1861/2011 men employed at the time of recruitment. Of these 1861, 296 (15.9%) had poor morphology; of the 2011with sperm count, 453 (22.5%) had low MSC; 654/1981 (33.0%) had either condition. Poor morphology, adjusted for confounding, was related to self-reported lifetime exposure to lead (OR=1.33; 95% CI 1.00 to 1.75). Low MSC was also related to self-reported lead and to hygienist-assessed glycol ether exposure. Self-reported use of paint stripper (OR=1.47; 95% CI 1.07 to 2.03) and lead, but not glycol ether, were significantly related to the combined case definition. CONCLUSIONS: While this study did not identify any occupational exposure uniquely related to sperm morphology, the capacity of the study to detect risk was increased by including morphology with sperm concentration and motility.

Does recall bias explain the association of mood disorders with workplace harassment?

Purpose: To determine the contribution of recall bias to the observed excess in mental ill-health in those reporting harassment at work. Methods: A prospective cohort of 1885 workers in welding and electrical trades was contacted every six months for up to 5 years, asking whether they were currently anxious or depressed and whether this was made worse by work. Only at the end of the study did we ask about any workplace harassment they had experienced at work. We elicited sensitivity and specificity of self-reported bullying from published reliability studies and formulated priors that reflect the possibility of over-reporting of workplace harassment (exposure) by those whose anxiety or depression was reported to be made worse by work (cases). We applied the resulting misclassification models to probabilistic bias analysis (PBA) of relative risks. Results: We observe that PBA implies that it is unlikely that biased misclassification due to the study subjects' states of mind could have caused the entire observed association. Indeed, the results demonstrated that doubling of risk of anxiety or depression following workplace harassment is plausible, with the unadjusted relative risk attenuated with understated uncertainty. Conclusions: It seems unlikely that risk of anxiety or depression following workplace harassment can be explained by the form of recall bias that we proposed.

Reported harassment and mental ill-health in a Canadian prospective cohort of women and men in welding and electrical trades.

OBJECTIVES: Experience of psychosocial environments by workers entering trade apprenticeships may differ by gender. We aimed to document perceived harassment and to investigate whether this related to mental ill-health. METHODS: Cohorts of workers in welding and electrical trades were established, women recruited across Canada and men from Alberta. Participants were recontacted every 6 months for up to 3 years (men) or 5 years (women). At each contact, they were asked about symptoms of anxiety and depression made worse by work. After their last regular contact, participants received a "wrap-up" questionnaire that included questions on workplace harassment. In Alberta, respondents who consented were linked to the administrative health database that recorded diagnostic codes for each physician contact. RESULTS: One thousand eight hundred and eighty five workers were recruited, 1,001 in welding trades (447 women), and 884 in electrical trades (438 women). One thousand four hundred and nineteen (75.3%) completed a "wrap up" questionnaire, with 1,413 answering questions on harassment. Sixty percent of women and 32% of men reported that they had been harassed. Those who reported harassment had more frequently recorded episodes of anxiety and depression made worse by work in prospective data. In Alberta, 1,242 were successfully matched to administrative health records. Those who reported harassment were more likely to have a physician record of depression since starting their trade. CONCLUSIONS: Tradeswomen were much more likely than tradesmen to recall incidents of harassment. The results from record linkage, and from prospectively collected reports of anxiety and depression made worse by work, support a conclusion that harassment resulted in poorer mental health.

Availability, use, and impact of workplace mental health supports during the COVID-19 pandemic in a Canadian cohort of healthcare workers.

We investigated the availability and use of workplace mental health (MH) supports during the COVID-19 pandemic in a Canadian cohort of healthcare workers (HCW) and measured anxiety and depression by the Hospital Anxiety and Depression Scale (HADS) completed at four contacts 2020-2022. Reports were available for 4400 HCW working with patients. Half the HCWs had a clinically significant HADS score at one or more contacts Access to MH supports increased during the pandemic, with 94% reporting access to some workplace support by 2022: 47% had made use of at least one support. 25% of those with high HADS scores used no support. Older women and men with depressive conditions were less likely to report use. Reported use of an Employee Assistance Program was associated with a reduction in HADS scores in the following months.

Excess risk of COVID-19 infection and mental distress in healthcare workers during successive pandemic waves: Analysis of matched cohorts of healthcare workers and community referents in Alberta, Canada.

OBJECTIVES: To investigate changes in risk of infection and mental distress in healthcare workers (HCWs) relative to the community as the COVID-19 pandemic progressed. METHODS: HCWs in Alberta, Canada, recruited to an interprovincial cohort, were asked consent to link to Alberta's administrative health database (AHDB) and to information on COVID-19 immunization and polymerase chain reaction (PCR) testing. Those consenting were matched to records of up to five community referents (CRs). Physician diagnoses of COVID-19 were identified in the AHDB from the start of the pandemic to 31 March 2022. Physician consultations for mental health (MH) conditions (anxiety, stress/adjustment reaction, depressive) were identified from 1 April 2017 to 31 March 2022. Risks for HCW relative to CR were estimated by fitting wave-specific hazard ratios. RESULTS: Eighty percent (3050/3812) of HCWs consented to be linked to the AHDB; 97% (2959/3050) were matched to 14,546 CRs. HCWs were at greater risk of COVID-19 overall, with first infection defined from either PCR tests (OR=1.96, 95%CI 1.76-2.17) or physician records (OR=1.33, 95%CI 1.21-1.45). They were also at increased risk for each of the three MH diagnoses. In analyses adjusted for confounding, risk of COVID-19 infection was higher than for CRs early in the pandemic and during the fifth (Omicron) wave. The excess risk of stress/adjustment reactions (OR=1.52, 95%CI 1.35-1.71) and depressive conditions (OR=1.39, 95%CI 1.24-1.55) increased with successive waves during the epidemic, peaking in the fourth wave. CONCLUSION: HCWs were at increased risk of both COVID-19 and mental ill-health with the excess risk continuing late in the pandemic.

RéSUMé: OBJECTIFS: Étudier l'évolution du risque d'infection et de problèmes de santé mentale (PSM) chez les travailleurs de la santé (TdS), comparé à la population générale, au cours de la pandémie de COVID-19. MéTHODES: Certains TdS de l'Alberta (Canada) participant à une cohorte interprovinciale, ont consenti à ce que la base administrative de santé de l'Alberta (AHDB) nous transmette leurs données de vaccination contre la COVID-19 et de tests d'amplification des acides nucléiques (TAAN). Ceux ayant consenti ont été appariés à un maximum de cinq témoins de population générale. Les diagnostics médicaux (par médecins) de COVID-19 ont été identifiés dans l'AHDB du début de la pandémie jusqu'au 31 mars 2022. Les consultations médicales pour PSM (anxiété, stress/troubles de l'adaptation, dépression) ont été identifiées entre le 1er avril 2017 et le 31 mars 2022. Les rapports de cotes (RC) comparant les TdS aux témoins de la population générale ont été estimés pour chaque vague d'infection. RéSULTATS: Quatre-vingts pourcent (80 %; 3050/3812) des TdS ont donné leur consentement à ce que leurs données nous soient transmises par l'AHDB; 97 % d'entre eux (2959/3050) ont été appariés à 14 546 témoins. Dans l'ensemble, les TdS étaient plus à risque de COVID-19, avec une première infection identifiée soit par les TANN (RC=1,96, IC de 95% 1,76-2,17), soit via les dossiers médicaux (RC=1,33, IC de 95% 1,21-1,45). Ils étaient également plus à risque pour chacun des trois problèmes de SM. Le risque de COVID-19 ajustés pour les facteurs de confusion était plus élevé que chez les témoins au début de la pandémie et durant la cinquième vague (variant Omicron). Les excès de risque de stress/troubles de l'adaptation (RC=1,52, IC de 95% 1,35-1,71) et de dépression (RC=1,39, IC de 95% 1,24-1,55) ont augmenté au fil des vagues de l'épidémie, avec un pic à la quatrième vague. CONCLUSION: Les TdS étaient plus à risque d'infection de COVID-19 et de troubles de santé mentale avec cet excès de risque se prolongeant plus tard dans la pandémie.

Work Characteristics, Workplace Support, and Mental Ill-Health in a Canadian Cohort of Healthcare Workers During the COVID-19 Pandemic.

OBJECTIVE: The aim of the study was to identify determinants of mental health in healthcare workers (HCW) during the COVID-19 pandemic. METHODS: A cohort of Canadian HCW completed four questionnaires giving details of work with patients, ratings of workplace supports, a mental health questionnaire, and substance use. Principal components were extracted from 23 rating scales. Risk factors were examined by Poisson regression. RESULTS: A total of 4854 (97.8%) of 4964 participants completed ratings and mental health questionnaires. Healthcare workers working with patients with COVID-19 had high anxiety and depression scores. One of three extracted components, 'poor support,' was related to work with infected patients and to anxiety, depression, and substance use. Availability of online support was associated with feelings of better support and less mental ill-health. CONCLUSIONS: Work with infected patients and perceived poor workplace support were related to anxiety and depression during the pandemic.

Determinants of SARS-CoV-2 IgG response and decay in Canadian healthcare workers: A prospective cohort study.

INTRODUCTION: Healthcare workers (HCWs) from an interprovincial Canadian cohort gave serial blood samples to identify factors associated with anti-receptor binding domain (anti-RBD) IgG response to the SARS-CoV-2 virus. METHODS: Members of the HCW cohort donated blood samples four months after their first SARS-CoV-2 immunization and again at 7, 10 and 13 months. Date and type of immunizations and dates of SARS-CoV-2 infection were collected at each of four contacts, together with information on immunologically-compromising conditions and current therapies. Blood samples were analyzed centrally for anti-RBD IgG and anti-nucleocapsid IgG (Abbott Architect, Abbott Diagnostics). Records of immunization and SARS-CoV-2 testing from public health agencies were used to assess the impact of reporting errors on estimates from the random-effects multivariable model fitted to the data. RESULTS: 2752 of 4567 vaccinated cohort participants agreed to donate at least one blood sample. Modelling of anti-RBD IgG titer from 8903 samples showed an increase in IgG with each vaccine dose and with first infection. A decrease in IgG titer was found with the number of months since vaccination or infection, with the sharpest decline after the third dose. An immunization regime that included mRNA1273 (Moderna) resulted in higher anti-RBD IgG. Participants reporting multiple sclerosis, rheumatoid arthritis or taking selective immunosuppressants, tumor necrosis factor inhibitors, calcineurin inhibitors and antineoplastic agents had lower anti-RBD IgG. Supplementary analyses showed higher anti-RBD IgG in those reporting side-effects of vaccination, no relation of anti-RBD IgG to obesity and lower titers in women immunized in early or mid-pregnancy. Sensitivity analysis results suggested no important bias in the self-report data. CONCLUSION: Creation of a prospective cohort was central to the credibility of results presented here. Serial serology assessments, with longitudinal analysis, provided effect estimates with enhanced accuracy and a clearer understanding of medical and other factors affecting response to vaccination.

Arsenic in drinking water and renal cancers in rural Bangladesh.

OBJECTIVES: Data on the role of arsenic in renal cancer are suggestive but inconclusive. The present analysis aimed to determine whether renal cancers were more likely in Bangladeshi villagers exposed to high arsenic concentration in well water and, if so, whether this excess was limited to transitional cell cancers (TCC) or occurred also for renal cell cancers (RCC). METHODS: Histology/cytology results from renal biopsies carried out at a single clinic in Dhaka, Bangladesh, from January 2008 to October 2011 were classified into four groups: RCC, TCC, other malignancy and benign. Patients aged ≥18 years using hand-pumped well water were identified by questionnaire, blind to diagnosis. Arsenic concentration was estimated from British Geological Survey reports for administrative area (thana) of residence. In a case-referent design (with benign results as referents), ORs were calculated by multilevel logistic regression adjusted for confounding. Time since well installation and smoking were examined by stratification. RESULTS: Among 1489 cases included, 896 were RCC, 90 TCC and 503 benign. Arsenic concentration was estimated for 301 thanas with 63% of cases and 40% referents with arsenic concentration ≥50 µg/L (p<0.001). Risk increased monotonically with arsenic concentration ≥50 µg/L for both cell types (RCC and TCC). Risk estimates were greater in thana with early well installation where risk was increased for RCC in exposure stratum 10<50 µg/L (OR=2.47 95% CI 1.52 to 4.01). Stratification by 'ever smoked' confirmed the presence of risk in non-smokers. CONCLUSIONS: The relationship between arsenic concentration and both RCC and TCC suggests that arsenic is a causal factor in renal cancer.