Quantile regressions as a tool to evaluate how an exposure shifts and reshapes the outcome distribution: A primer for epidemiologists.

Quantifying how an exposure affects the entire outcome distribution is often important, e.g., for outcomes such as blood pressure which have non-linear effects on long-term morbidity and mortality. Quantile regressions offer a powerful way of estimating an exposure's relationship with the outcome distribution but remain underused in epidemiology. We introduce quantile regressions with a focus on distinguishing estimators for quantiles of the conditional and unconditional outcome distributions. We also present an empirical example in which we fit mean and quantile regressions to investigate educational attainment's association with later-life systolic blood pressure (SBP). We use data on 8,875 US-born respondents aged 50+ years from the US Health and Retirement Study. More education was negatively associated with mean SBP. Conditional and unconditional quantile regressions both suggested a negative association between education and SBP at all levels of SBP, but the absolute magnitudes of these associations were higher at higher SBP quantiles relative to lower quantiles. In addition to showing that educational attainment shifted the SBP distribution left-wards, quantile regression results revealed that education may have reshaped the SBP distribution through larger protective associations in the right tail, thus benefiting those at highest risk of cardiovascular diseases.

Interruptions in HIV and Behavioral Health Care for Criminal-Legal Involved People Living with HIV Following Implementation of Decarceration and Shelter in Place in San Francisco, California.

Decarceration policies, enacted for SARS-CoV-2 mitigation in carceral settings, potentially exacerbated barriers to care for people living with HIV (PWH) with criminal legal involvement (CLI) during Shelter-in-Place (SIP) by limiting opportunities for engagement in provisions of HIV and behavioral health care. We compared health care engagement for PWH with CLI in San Francisco, California before and after decarceration and SIP using interrupted time series analyses. Administrative data identified PWH booked at the San Francisco County Jail with at least one clinic encounter from 01/01/2018-03/31/2020 within the municipal health care network. Monthly proportions of HIV, substance use, psychiatric and acute care encounters before (05/01/2019-02/29/2020) and after (03/01/2020-12/31/2020) SIP and decarceration were compared using Generalized Estimating Equation (GEE) log-binomial and logistic regression models, clustering on the patient-level. Of 436 patients, mean age was 43 years (standard-deviation 11); 88% cisgender-male; 39% white, 66% homeless; 67% had trimorbidity by Elixhauser score (medical comorbidity, psychotic disorder or depression, and substance use disorder). Clinical encounters immediately dropped following SIP for HIV (aOR = 0.77; 95% CI: 0.67, 0.90) and substance use visits (aRR = 0.83; 95% CI: 0.70, 0.99) and declined in subsequent months. Differential reductions in clinical encounters were seen among Black/African Americans (aRR = 0.93; 95% CI: 0.88, 0.99) and people experiencing homelessness (aRR = 0.92; 95% CI: 0.87, 0.98). Significant reductions in care were observed for PWH with CLI during the COVID-19 pandemic, particularly among Black/African Americans and people experiencing homelessness. Strategies to End the HIV Epidemic must improve engagement across diverse care settings to improve outcomes for this key population.

Efficacy of hydrogen peroxide to reduce Gyrodactylus species infestation density on four fish species.

OBJECTIVE: The ability to effectively treat parasitic infestations of fish is of high importance for fish culture facilities. However, tools or approved therapies for treating infestations on fish are limited. This paper summarizes results from four separate clinical field studies that evaluated the efficacy of hydrogen peroxide (H2 O2 ; 35% PEROX-AID) for reducing Gyrodactylus spp. infestation density. METHODS: Three species of Gyrodactylus were studied (G. salmonis, hosts: Brook Trout Salvelinus fontinalis and Lake Trout S. namaycush; G. freemani, host: Yellow Perch Perca flavescens; G. hoffmani, host: Fathead Minnow Pimephales promelas) before and after the application of immersion H2 O2 therapy. RESULT: Parasite density was significantly reduced for each parasite × host combination to which H2 O2 therapy was applied. Two clinical field studies in salmonids were found to demonstrate substantial effectiveness that enabled 35% PEROX-AID approval. CONCLUSION: Further assessments of Gyrodactylus spp. could expand the use of H2 O2 for controlling these parasites in aquaculture. Specifically, H2 O2 was effective at all levels tested (50 or 75 mg H2 O2 /L for 60 min for the Yellow Perch and Fathead Minnow clinical field studies; 100 or 150 mg H2 O2 /L for 30 min regardless of salt pre-treatment for the Brook Trout study; and 100 mg H2 O2 /L for 30 min or 50 mg H2 O2 /L for 60 min for the Lake Trout study).

First-generation college graduates have similar depressive symptoms in midlife as multi-generational college graduates.

Purpose: Higher education may protect an individual against depressive symptoms, yet, disadvantaged socioeconomic status (SES) during childhood, often measured by lower parental education, may put them at higher risk for depressive symptoms later in life. This study evaluates if midlife depression is similar for first-generation and multi-generation college graduates. Methods: For US Health and Retirement Study (HRS) participants ages 55-63 (N = 16,752), we defined a 4-category exposure from parents' (highest of mother or father's) and participant's own years of education, with 16 years indicating college completion: multi-gen (both ≥ 16 years: reference); first-gen (parents <16; own ≥ 16); only parent(s) (parents ≥ 16; own <16); and neither (both <16) college graduates across three birth cohorts. We used linear regressions to evaluate relationships between college completion and depressive symptoms measured by an 8-item Center for Epidemiologic Studies - Depression (CES-D) scale. Models pooled over time evaluated differences by sex, race/ethnicity, and birthplace. Results: First-gen and multi-gen college graduates averaged similar depressive symptoms in midlife (ß: 0.01; 95% CI: 0.15, 0.13). Results were similar by sex and race/ethnicity. Conclusion: Consistent with resource substitution theory, college completion may offset the deleterious effects of lower parental education on midlife depressive symptoms for first-generation graduates.