The effect of mild to moderate COVID-19 infection on the cardiorespiratory fitness of firefighters.

Introduction: An adequate level of cardiorespiratory fitness (CRF) is critical for firefighters to perform the strenuous and physiologically demanding work of firefighting safely and effectively. The coronavirus disease 2019 (COVID-19) has been shown to negatively impact CRF in both the acute phase and longer-term following infection. This study aimed to determine changes to the CRF of firefighters pre- to post-mild to moderate COVID-19 infection and to investigate the impact of days past COVID-19 infection on change in CRF. Methods: CRF measures from cardiopulmonary exercise testing (CPET) at annual occupational health exams that occurred pre-COVID-19 infection in 2019 were obtained for firefighters from seven Arizona fire departments. Measures were compared to CPET evaluations from annual health exams the following year in a cohort of firefighters who self-reported mild to moderate illness following COVID-19 infection between exams. Results: Among a cohort of 103 firefighters, mean age 40 ± 9 years, CRF [as measured by peak oxygen consumption (VO2)] declined by an average of 2.55 ml·kg-1·min-1 or 7.3% (d = -0.38, p < 0.001) following COVID-19 infection (mean time from COVID-19 infection to CPET was 110 ± 78 days). The number of days past COVID-19 infection showed a small, yet significant, relationship to peak VO2 (r = 0.250, p = 0.011). Estimated marginal effects indicated that when biological sex, age, and BMI are controlled for, predicted peak VO2 returned to pre-COVID-19 values ~300 days after COVID-19 infection. Conclusion: Peak VO2 (ml·kg-1·min-1) declined 7.3% among firefighters an average of 110 days past reporting mild to moderate COVID-19 infection. This decrease has implications for the operational readiness and safety of firefighters.

Subclinical Cardiac Dysfunction is Associated with Reduced Cardiorespiratory Fitness and Cardiometabolic Risk Factors in Firefighters.

BACKGROUND: Past studies have documented the ability of cardiopulmonary exercise testing to detect cardiac dysfunction in symptomatic patients with coronary artery disease. Firefighters are at high risk for work-related cardiac events. This observational study investigated the association of subclinical cardiac dysfunction detected by cardiopulmonary exercise testing with modifiable cardiometabolic risk factors in asymptomatic firefighters. METHODS: As part of mandatory firefighter medical evaluations, study subjects were assessed at 2 occupational health clinics serving 21 different fire departments. Mixed effects logistic regression analyses were used to estimate odds ratios (ORs) and account for clustering by fire department. RESULTS: Of the 967 male firefighters (ages 20-60 years; 84% non-Hispanic white; 14% on cardiovascular medications), nearly two-thirds (63%) had cardiac dysfunction despite having normal predicted cardiorespiratory fitness (median peak VO2 = 102%). In unadjusted analyses, cardiac dysfunction was significantly associated with advanced age, obesity, diastolic hypertension, high triglycerides, low high-density lipoprotein (HDL) cholesterol, and reduced cardiorespiratory fitness (all P values < .05). After adjusting for age and ethnicity, the odds of having cardiac dysfunction were approximately one-third higher among firefighters with obesity and diastolic hypertension (OR = 1.39, 95% confidence interval [CI] = 1.03-1.87 and OR = 1.36, 95% CI = 1.03-1.80) and more than 5 times higher among firefighters with reduced cardiorespiratory fitness (OR = 5.41, 95% CI = 3.29-8.90). CONCLUSION: Subclinical cardiac dysfunction detected by cardiopulmonary exercise testing is a common finding in career firefighters and is associated with substantially reduced cardiorespiratory fitness and cardiometabolic risk factors. These individuals should be targeted for aggressive risk factor modification to increase cardiorespiratory fitness as part of an outpatient prevention strategy to improve health and safety.

Cardiometabolic health among United States firefighters by age.

Firefighting is strenuous work that results in considerable cardiovascular strain. Sudden cardiac events are the leading cause of duty-related death in the fire service. This cross-sectional study examined cardiometabolic measures and prevalence of risk factors in firefighters by age and sex and compare these data to the general population. Data obtained at medical exams (2015-2018) from 4279 male and 234 female career firefighters at four occupational health clinics in the United States were analyzed. Estimates for the general population were obtained using the 2015-16 National Health and Nutrition Examination Survey fasting subsample. Linear regression models stratified by sex with age modelled as a continuous variable were used to examine general trends. Point estimates across age groups (20-29, 30-39, 40-49, and 50-59 year olds) for cardiometabolic measures were reported. Among the total sample, 36% were obese and 25% had low HDL cholesterol. Females had significantly lower body mass index (BMI), LDL cholesterol, triglycerides and blood glucose than males. A significant quadratic relationship of age with BMI, total cholesterol, LDL cholesterol, and triglycerides was found in males with increasing values peaking between 45 and 50 years. Total cholesterol and LDL cholesterol increased with age among females. Blood glucose increased with age in both sexes. Firefighters had similar or better cardiometabolic health profiles than the US general population; however, both samples had a concerning prevalence of cardiometabolic risk factors among individuals ≥ 40 years of age. Health professionals and fire service members alike should consider prevention efforts among young firefighters and better treatment among older firefighters.

Cardiovascular Disease Risk Factors by BMI and Age in United States Firefighters.

OBJECTIVE: This study examined cardiovascular disease risk factors by BMI category in firefighters, the association of BMI and age with risk factor prevalence, and the prevalence of risk factors by BMI category within age groups. METHODS: Cardiovascular measures from the medical evaluations of 4,453 firefighters, performed between 2015 and 2018 at four occupational health clinics in the United States (South-West Cohort, Mid-Atlantic Cohort, South-East Cohort, and Mid-West Cohort), were analyzed cross-sectionally by BMI and age categories. RESULTS: Among female firefighters with normal weight, 25% had high blood pressure, 8% had low high-density lipoprotein cholesterol, and 0% had high glucose, whereas the prevalence in female firefighters with obesity was 57%, 45%, and 11%, respectively. Among male firefighters, there were independent and significant associations of BMI and age for the prevalence of high blood pressure, high cholesterol, high triglycerides, and high glucose. Higher BMI category was associated with a higher prevalence of high blood pressure, high triglycerides, and low high-density lipoprotein cholesterol within all age groups and with a higher prevalence of high glucose and high cholesterol within ages 40 to 49 and 50 to 59 years. CONCLUSIONS: An increasing prevalence of risk factors with older age and higher BMI suggests that preventive strategies should be initiated in younger firefighters and aggressively promoted or mandated throughout firefighters' careers.

Hypertension in the United States Fire Service.

Hypertension is a major risk factor for atherosclerotic cardiovascular disease and cardiac remodeling and is associated with an increased risk of sudden cardiac events, the leading cause of duty-related death in the fire service. We assessed systemic blood pressures and prevalence of hypertension among US firefighters by decade of life. Medical records of career firefighters (5063 males and 274 females) from four geographically diverse occupational health clinics were assessed. Hypertension was defined as systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg, or taking antihypertensive medication. Results from the firefighter sample were compared to the US general population (2015-2016 and 2017-2018 National Health and Nutrition Examination Surveys). Among the total sample, 69% of firefighters met the criteria for hypertension and 17% were taking antihypertensive medications. Percentages of hypertensive male and female firefighters were 45% and 11% among 20-29 years old, respectively, and increased to 78% and 79% among 50-59 years old, respectively. Compared to the general population, male firefighters had a higher prevalence of hypertension (p < 0.05) across all age groups (11-16% higher). In order to improve firefighter health and protect against sudden incapacitation in this public safety occupational group, increased efforts are necessary to screen for and manage high blood pressure.

A Cross-Sectional Examination of 10-Year Atherosclerotic Cardiovascular Disease Risk Among US Firefighters by Age and Weight Status.

OBJECTIVE: Examine atherosclerotic cardiovascular disease (ASCVD) risk scores by age and weight status in career firefighters. METHODS: Medical examinations for firefighters more than or equal to 40 years (n = 644) were examined. ASCVD 10-year risk scores were calculated from sex- and race-specific equations and were reported by three age (40 to 44.9, 45 to 49.9, more than or equal to 50 years) and weight (normal, overweight, obese) categories. RESULTS: Mean risk scores were 1.8%, 3.5%, and 6.2% for firefighters 40 to 44.9, 45 to 49.9, and more than or equal to 50 years, respectively. The association of weight status with increased ASCVD risk was higher (P < 0.01) among older firefighters, where risk was 0.8% (95% confidence interval [CI]: 0.6 to 1.1) and 2.3% (95% CI: 2.0 to 2.6) among normal versus obese 40 to 44.9 year olds, and 4.1% (95% CI: 3.1 to 5.3) and 7.8% (95% CI: 6.7 to 8.9) among normal versus obese more than or equal to 50 year olds. CONCLUSIONS: While firefighters cannot avoid aging, physicians should counsel firefighters with weight-maintenance or weight-loss advice to prevent and manage elevated ASCVD risk.

Cardiovascular Risk Factor Reduction in First Responders Resulting From an Individualized Lifestyle and Blood Test Program: A Randomized Controlled Trial.

OBJECTIVE: We tested the hypothesis that a lifestyle program would improve risk factors linked to cardiovascular disease (CVD) in first responders. METHODS: A 1-year cluster-randomized controlled clinical trial in 10 cities. Participants were 175 first responders, with increased waist circumference and/or low levels of large (α1) high-density lipoprotein (HDL) particles. The intervention group received personalized online tools and access to telephonic coaching sessions. RESULTS: At 1 year the intervention significantly reduced body weight (P = 0.004) and waist circumference (P = 0.002), increased α1 HDL (P = 0.01), and decreased triglyceride (P = 0.005) and insulin concentrations (P = 0.03). Program adherence was associated with weight loss (P = 0.0005) and increases in α1 HDL (P = 0.03). CONCLUSIONS: In first responders, a personalized lifestyle intervention significantly improved CVD risk factors in proportion to program adherence. Changes in large HDL particles were more sensitive indicators of lifestyle changes than HDL-cholesterol measurement. CLINICAL TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT03322046.