PCP Prophylaxis Nonadherence Table 3. Primary reason for not taking medications to prevent Pneumocystis jirovecii pneumonia (PCP) listed by 264 persons who were nonadherent with primary PCP prophylaxis – Supplement to HIV/AIDS Surveillance (SHAS) project, 2000–2004. Primary Reason for Not Taking PCP Medications as Prescribed Nonadherent with Primary PCP Prophylaxis Side effects Limited access, mental health, or living situation Cannot afford medications Do not understand either how to take medications or why they were prescribed Cannot get to clinic or physician’s office ‘‘Back on street’’ Depressed In jail or prison Issues with scheduling, memory, or lack of perceived necessity Cannot fit taking medications into schedule Often forget to take medications ‘‘Take too many medications’’ Do not believe in them or do not believe they need to take them doi:10.1371/journal.pone.0005002.t003 associated with nonadherence to PCP prophylaxis or ART [11,23,24]. Our findings may differ from those of other investigators because we were able to control more completely for potentially confounding variables or, with respect to the number of pills taken daily, because we used a different measure for pill burden that included all medications prescribed and not just ART medications. Forgetting to take PCP prophylaxis was the most common reason provided by participants in our analysis, followed by concern about side effects and inability to fit taking the medication(s) into one’s schedule, which parallels reasons given for nonadherence to ART among SHAS participants in a separate analysis [23]. Forgetting to take medications has previously been reported to be an important reason for nonadherence to PCP prophylaxis [11], ART [27], and prescribed therapy for other conditions [28,29]. Structural barriers such as limited access to healthcare or medications were not prominent as reasons for nonadherence in our analysis. This study has several imitations. Because this was an interview study, our findings are subject to recall and social desirability bias [30]. However, asking subjects about their adherence to primary PCP prophylaxis in the month before the interview should have reduced recall bias. Because social desirability would be expected to lead subjects to underreport nonadherence to medications, our estimate may be a minimum one [31]. Because hospitals that participated in areas which used facility-based recruitment may not have been representative of all facilities that provide care to HIV-infected persons in these areas, and persons recruited and interviewed by SHAS sites were not representative of all HIV- infected persons, or of all HIV-infected persons in care, our findings are subject to selection bias. In addition, limited or no information was collected in the interview about a number of factors that may be important for nonadherence, including social support, isolation, treatment efficacy, and self-efficacy [32,33]. Despite these limitations, the SHAS surveillance system represents the largest survey of HIV-infected persons in the U.S. and therefore has the most complete data to assess self-reported adherence to PCP prophylaxis. N = 264 n (%) 57 (21.6) 36 (13.6) 2 (0.8) 3 (1.1) 21 (8.0) 4 (1.5) 4 (1.5) 2 (0.8) 171 (64.8) 35 (13.3) 119 (45.1) 6 (2.3) 11 (4.2) Nonadherence to PCP prophylaxis is an important contributor to adverse clinical events, and nonadherence to relatively simple regimens used to protect against PCP suggests that there may be greater challenges with adherence to ART regimens, which are more complicated [11]. We found that an appreciable proportion of HIV-infected persons were nonadherent to prescribed medica- tions to prevent PCP, and that persons who were nonadherent to PCP prophylaxis were much more likely to be nonadherent to ART. Providers should inquire about adherence to prescribed medications to prevent PCP at every HIV care visit, paying particular attention to persons who use illicit drugs, have mental health issues, have low CD4 cell counts, and are nonadherent to ART or medications prescribed for other conditions. These variables should be triggers for providers to consider the complex issue of adherence. Providers should take every opportunity to educate their patients about the importance of compliance with ART and medications to prevent opportunistic infections, discuss the possible side effects of prescribed medications, and assist patients about ways to remember to take their medications as prescribed. In addition, providers should regularly ask HIV- infected patients about illicit drug use and mental health issues and treat or refer persons with substance abuse and/or mental illnesses to ensure optimal adherence to prescribed medications. Although few studies have evaluated factors associated with nonadherence or ways to improve adherence to medications to prevent PCP, the commonality of associated factors for nonadherence to PCP prophylaxis and ART suggests that interventions for ART adherence may be also be used to improve adherence to PCP prophylaxis. Studies evaluating adherence to ART, prophylaxis against PCP and other opportunistic infections, and prescribed medications for other conditions may shed light on how to improve adherence and quality of life and reduce morbidity and mortality among HIV-infected persons. Acknowledgments We would like to acknowledge the contributions of the SHAS project principal investigators and project officers: Vjollca Berisha and Rick PLoS ONE | www.plosone.org 6 March 2009 | Volume 4 | Issue 3 | e5002