In this study of 489 participants receiving outpatient HIV primary care, overall patient satisfaction with care is positively related to retention in HIV care and adherence to HAART, which in turn serve as key determinants of HIV suppression. The data suggest that patient satisfaction may provide a way to improve HIV outcomes through its positive influences on adherence to HAART and retention in HIV care. This finding suggests that patient-centered interventions designed to improve the care experience could serve as an innovative method for optimizing HIV outcomes.
The National Council on Patient Information and Education's report, Enhancing Prescription Medicine Adherence: A National Action Plan
, states that medication nonadherence has reached crisis proportions 
. The report calls for adherence research that explores innovative ways to increase patient uptake of proven therapies. Successful interventions not only need to demonstrate efficacy and effectiveness, but also the capacity for ultimate adoption, implementation and maintenance in real-world settings.
Retention in HIV care is a critical step for achieving long-term survival with HIV infection 
. Furthermore, HIV primary care guidelines recognize the importance of retention in HIV care as a precursor to adherence to HAART 
. Successful strategies to improve retention in HIV care and adherence to HAART require an understanding of retention and adherence behavior and the complex interplay between biological, psychological, behavioral, social and health systems drivers. They also require a multi-level, multi-component approach to responding to the needs and concerns of individual patients. Simple practices shown to improve adherence include reductions in dose frequency and the use of adherence aids (e.g. pill boxes, text reminders) 
. Successful interventions to improve retention in HIV care have required more complex and intensive efforts to decrease unmet needs, decrease structural barriers and reduce substance abuse 
. Given the suboptimal state of retention in HIV care and adherence to HAART, it is critical to identify additional modifiable drivers to inform evidence-based interventions to optimize HIV care.
Patient satisfaction represents an innovative focus for retention and adherence intervention efforts. Its innovation derives from applying the business model of customer satisfaction to improve patient adherence to care. Additionally, interventions to improve patient satisfaction with the overall care experience are not directly dependent on efforts to explicitly change patient behavior. Patient satisfaction reflects the patient's perception of the entire care process, and improving satisfaction metrics lies within the power of a clinic or institution.
Research indicates that provider and organizational factors play a large role in how patients evaluate their provider and overall clinic care 
. Several empirical studies have shown that training in patient-centered communication and audit feedback can help providers improve communication skills in ways that increase patient satisfaction 
. Furthermore, organizational factors like increasing the time allowed for provider visits and ensuring continuity of care with the same provider can increase patients' satisfaction with their provider and overall care 
. Continued progress in studying patient satisfaction requires not only additional evaluation of its effects on health outcomes, but also developing an understanding of the particular mechanisms or processes through which beneficial results are achieved.
The development of successful interventions to improve retention in HIV care and adherence to HAART requires a better understanding of how patient satisfaction impacts those constructs. The exact mechanisms explaining the linkages between these constructs remain unclear. Additionally, it remains unclear which component or components of the care experience most strongly influence retention and adherence. Several studies, including a previous study based on this dataset, have reported that patients' evaluation of their provider correlates the strongest with their overall satisfaction 
. However, the provider characteristic most predictive of overall patient satisfaction may differ from those that may affect clinical outcomes. For example, provider training in problem solving focused adherence counseling techniques, as proposed in Wilson et al. 
, may have more influence on adherence than providers' interpersonal and general communication skills. Future research directions need to include prospective quantitative studies to: 1) better understand which component or components of the care experience are most predictive of overall patient satisfaction, medication adherence and retention in HIV care, 2) quantify how the strength of association changes over time as care progresses and what factors significantly influence those trends, and 3) establish causal direction.
This study has several methodological strengths. Our practice-based model incorporates the business model of customer satisfaction with the clinical end point of HIV suppression. The study took place at 2 clinic sites. It primarily included a low-income minority population, which often has low rates of adherence to care and worse clinical outcomes 
. This population would stand to gain the most from interventions to improve adherence to care.
This study has certain limitations. Although our study supports the proposed causal linkages between overall patient satisfaction, retention in HIV care, adherence to HAART, and HIV suppression, correlational data cannot provide definitive evidence of causality. Emerging consensus, however, suggests that such data, when examined through structural equation modeling, can help researchers articulate, clarify and evaluate causal explanations between constructs of interest 
. Study eligibility required enrollment in clinic for at least one year and thus excluded patients new to HIV clinic. New clinic patients may have greater risk of being lost to follow-up. At the same time, new clinic patients have not formed any behavioral patterns of retention or adherence yet, may be more impressionable 
, and as a result, initial care experiences may have a greater effect on retention and adherence. At present, the relationship between satisfaction and adherence to HIV care in new clinic patients remains unclear. Furthermore, participants received HIV care at the VA and a public clinic, and study findings may not generalize to patients in other settings. Lastly, our model's explanatory power is limited to its included constructs. Our model should be extended in further research by including other predictors of retention in HIV care and adherence to HAART (e.g. patient attributes like adherence self-efficacy and outcome expectations, provider attributes like adherence problem solving counseling skills, etc). The extension of our model to include these and other variables may clarify patient satisfaction's relative contribution to retention and adherence.
This study identified retention in HIV care and adherence to HAART as intervening constructs through which patient satisfaction influences HIV outcomes. Our data raises the intriguing possibility that interventions aimed at improving the patient care experience by improving contextual components of care (i.e. who, where and how care is provided) could affect outcomes without actually targeting objective clinical performance measures. Our findings suggest that patient satisfaction could serve as an innovative target for interventions to improve HIV outcomes.