In a review of the literature from 1948 to 2001, 122 studies were found that correlated structural or functional social support with patient adherence to medical regimens. Meta-analyses establish significant average r-effect sizes between adherence and practical, emotional, and unidimensional social support; family cohesiveness and conflict; marital status; and living arrangement of adults. Substantive and methodological variables moderate these effects. Practical support bears the highest correlation with adherence. Adherence is 1.74 times higher in patients from cohesive families and 1.53 times lower in patients from families in conflict. Marital status and living with another person (for adults) increase adherence modestly. A research agenda is recommended to further examine mediators of the relationship between social support and health.

We describe the history and current status of the meta-analytic enterprise. The advantages and historical criticisms of meta-analysis are described, as are the basic steps in a meta-analysis and the role of effect sizes as chief coins of the meta-analytic realm. Advantages of the meta-analytic procedures include seeing the "landscape" of a research domain, keeping statistical significance in perspective, minimizing wasted data, becoming intimate with the data summarized, asking focused research questions, and finding moderator variables. Much of the criticism of meta-analysis has been based on simple misunderstanding of how meta-analyses are actually carried out. Criticisms of meta-analysis that are applicable are equally applicable to traditional, nonquantitative, narrative reviews of the literature. Much of the remainder of the chapter deals with the processes of effect size estimation, the understanding of the heterogeneity of the obtained effect sizes, and the practical and scientific importance of the effect sizes obtained.

Compared with nondepressed patients, the odds are 3 times greater that depressed patients will be noncompliant with medical treatment recommendations. Recommendations for future research include attention to causal inferences and exploration of mechanisms to explain the effects. Evidence of strong covariation of depression and medical noncompliance suggests the importance of recognizing depression as a risk factor for poor outcomes among patients who might not be adhering to medical advice.

Overall, the outcome difference between high and low adherence is 26%. According to a stringent random effects model, adherence is most strongly related to outcomes in studies of nonmedication regimens, where measures of adherence are continuous, and where the disease is chronic (particularly hypertension, hypercholesterolemia, intestinal disease, and sleep apnea). A less stringent fixed effects model shows a trend for higher adherence-outcome correlations in studies of less serious conditions, of pediatric patients, and in those studies using self-reports of adherence, multiple measures of adherence, and less specific measures of outcomes. Intercorrelations among moderator variables in multiple regression show that the best predictor of the adherence-outcome relationship is methodological-the sensitivity/quality of the adherence assessment.

This review offers insights into the literature on patient adherence, providing direction for future research. A focus on reliability and validity of adherence measurement and systematic study of substantive and methodologic moderators are recommended for future research on patient adherence.

Background-Numerous empirical studies from various populations and settings link patient treatment adherence to physician-patient communication. Meta-analysis allows estimates of the overall effects both in correlational research and in experimental interventions involving the training of physicians' communication skills.

The revised UCLA Loneliness Scale (ULS-20) and a four-item short form (ULS-4) are widely used in personality research (Russell, Peplau, & Cutrona, 1980). In an exploratory factor analysis of the ULS-20, we identified eight items that loaded substantially on the first factor. These items were combined to form an alternative short-form measure, the ULS-8. The results of this study indicate that the ULS-8 is reliable, valid, and a better substitute for the ULS-20 than is the ULS-4. Consistent with the previous research, the loneliness measures (ULS-20, ULS-8, ULS-4) were strongly related to socially undesirable personality characteristics, but loneliness was uncorrelated with the six different health-related behaviors (exercise, meal regularity, alcohol use, hard drug use, smoking, and hours of sleep) assessed in this study.

The influence of physicians' attributes and practice style on patients' adherence to treatment was examined in a 2-year longitudinal study of 186 physicians and their diabetes, hypertension, and heart disease patients. A physician-level analysis was conducted, controlling for baseline patient adherence rates and for patient characteristics predictive of adherence in previous analyses. General adherence and adherence to medication, exercise, and diet recommendations were examined. Baseline adherence rates were associated with adherence rates 2 years later. Other predictors were physician job satisfaction (general adherence), number of patients seen per week (medication), scheduling a follow-up appointment (medication), tendency to answer patients' questions (exercise), number of tests ordered (diet), seriousness of illness (diet), physician specialty (medication, diet), and patient health distress (medication, exercise).