Question

Based on the reading below, identify the dependent variable in this study.

Objectives. We estimated the risk of HIV associated with sexually transmitted infection (STI) history during adolescence. Methods. We retrospectively studied a cohort of adolescents (n = 75 273, born in 1985–1993) who participated in the Philadelphia High School STD Screening Program between 2003 and 2010. We matched the cohort to STI and HIV surveillance data sets and death certificates and performed Poisson regression to estimate the association between adolescent STI exposures and subsequent HIV diagnosis.  Results. Compared with individuals reporting no STIs during adolescence, adolescents with STIs had an increased risk for subsequent HIV infection (incidence rate ratio [IRR] for adolescent girls = 2.6; 95% confidence interval [CI] = 1.5, 4.7; IRR for adolescent boys = 2.3; 95% CI = 1.7, 3.1). Risk increased with number of STIs. The risk of subsequent HIV infection was more than 3 times as high among those with multiple gonococcal infections during adolescence as among those with none.  Conclusions. Effective interventions that reduce adolescent STIs are needed to avert future STI and HIV acquisition. Focusing on adolescents with gonococcal infections or multiple STIs might have the greatest impact on future HIV risk.

Answer 1

We observe following two statements in the analysis and report.

1. Compared with individuals reporting no STIs during adolescence, adolescents with STIs had an increased risk for subsequent HIV infection.
2. Effective interventions that reduce adolescent STIs are needed to avert future STI and HIV acquisition.

Clearly, independent variable is 'number of STIs' (sexually transmitted infection) upon which the variable 'risk for HIV infection' is dependent.

Hence, the dependent variable in the study is risk for HIV infection.