Comparing HIV case detection in prison during opt-in vs. opt-out testing policies.

Abstract

To the Editors: INTRODUCTION Routine HIV screening in health care settings, including prisons and jails, is recommended by the US Centers for Disease Control and Prevention to enhance the detection of HIV infection.1,2 A centerpiece of this strategy is opt-out HIV screening whereby patients are informed that testing will be conducted unless they decline the test. Although incarceration is considered an opportunity to detect HIV and initiate or restart HIV care,3–6 there are few data describing the performance of an opt-out testing policy in prisons, where HIV prevalence is several-fold that found in the general population.3 In November 2008, the North Carolina Department of Public Safety (NCDPS) Division of Adult Correction changed its HIV screening policy for incoming inmates from opt-in to opt-out testing. At the time of the policy change, we were conducting a HIV seroprevalence study among incoming prisoners.7 The co-occurrence of the change in policy and our seroprevalence study provided a natural experiment to assess the impact of the testing policy on HIV case detection of both newly diagnosed and previously diagnosed cases. METHODS This study was approved by the University of North Carolina Institutional Review Board, the NCDPS Human Subjects Review Committee, and the Office of Human Research Protections at the US Department of Health and Human Services (DHHS). Study Population and Setting All sentenced individuals entering the NCDPS between June 2008 and April 2009 were studied. Entering inmates underwent HIV screening within 2 weeks of prison entry. Before the change in policy (June 1 to October 31, 2008), HIV testing was offered under opt-in conditions, wherein a prison nurse conducted pretest counseling and asked inmates if they wanted to be tested. After the policy change (November 1, 2008 to April 15, 2009), HIV testing was provided in an opt-out manner, in which inmates were informed that they would be tested for HIV unless they declined testing. Data Sources and Linkage To determine whether HIV cases were detected or missed by prison system screening, we linked individual-level records from the prison system's HIV test (referred to hereafter as the Prison Test) and the HIV test we conducted to assess seroprevalence (referred to hereafter as the Study Test), which used excess blood from mandatory syphilis testing.7 We also determined whether incoming prisoners had been previously diagnosed with HIV, documented by NC DHHS record. These testing and diagnosis data were integrated into a single database of all sentenced prisoners during the study period. Before populating the database with results from the Study Test, prisoner identifiers were removed. Statistical Considerations The primary goal of the analysis was to estimate the difference across opt-in and opt-out testing policies in the annual number of cases detected by the prison system. Accordingly, we estimated the risk difference (RD) in case detection across testing policies, RD = probability (case detection|opt-out) – probability (case detection|opt-in). We then multiplied the estimated RD by an estimate of the annual number of HIV cases entering the prison system to estimate the annual difference in the number of cases detected under opt-out as compared with opt-in testing. We also assessed the potential influence on our results of confounding and of missing HIV status data (ie, those missing a Prison HIV Test, Study HIV Test, and with no record of a state diagnosis) using, respectively, multivariable regression models and both multiple imputation and a series of deterministic sensitivity analyses. The primary data analyses were conducted using SAS version 9.2 (Cary, NC). A full description of sensitivity analyses methods are available by request to the corresponding author. RESULTS During the study period, 23,373 sentenced prisoners (10,756 during opt-in and 12,617 during opt-out) entered the NCDPS (Fig. 1). A Study HIV Test was available for 94.7% (n = 22,134) of all incoming prisoners (opt-in: 96.0%, opt-out: 93.6%, P < 0.001). Of the 94.7%, 320 were HIV seropositive. Among the 5.3% (n = 1239) of inmates who were missing a Study HIV Test,7 48 cases were identified by the Prison Test and state record (n = 36) or by state record alone (n = 12). Of the 368 total HIV cases, there were 177 during opt-in and 191 during opt-out, resulting in respective HIV prevalence estimates of 1.7% (95% CI: 1.5 to 1.9) and 1.5% (95% CI: 1.3 to 1.8); these estimates were not statistically different (P = 0.34).FIGURE 1: Prison HIV testing among HIV+ prisoners entering the North Carolina state prison system under opt-in and opt-out testing policies, 2008–2009.HIV Screening and Probability of Case Detection Under Opt-In and Opt-Out Conditions The proportion of entering inmates receiving an HIV test during opt-in, 58.8%, and during opt-out testing, 95.2%, differed significantly (P < 0.001). The estimated probability of detecting a case among those without a