The estimated nonadherence rates, overall and by transplant type, allow clinicians to gauge patient risk and target resources accordingly. Nonadherence rates in some areas--including immunosuppressant use--appear unacceptably high. Weak correlations of most patient psychosocial factors with nonadherence suggest that attention should focus on other classes of variables (e.g., provider-related and systems-level factors), which may be more influential.
Longitudinal studies have a prominent role in psychiatric research; however, statistical methods for analyzing these data are rarely commensurate with the effort involved in their acquisition. Frequently the majority of data are discarded and a simple end-point analysis is performed. In other cases, so called repeated-measures analysis of variance procedures are used with little regard to their restrictive and often unrealistic assumptions and the effect of missing data on the statistical properties of their estimates. We explored the unique features of longitudinal psychiatric data from both statistical and conceptual perspectives. We used a family of statistical models termed random regression models that provide a more realistic approach to analysis of longitudinal psychiatric data. Random regression models provide solutions to commonly observed problems of missing data, serial correlation, time-varying covariates, and irregular measurement occasions, and they accommodate systematic person-specific deviations from the average time trend. Properties of these models were compared with traditional approaches at a conceptual level. The approach was then illustrated in a new analysis of the National Institute of Mental Health Treatment of Depression Collaborative Research Program dataset, which investigated two forms of psychotherapy, pharmacotherapy with clinical management, and a placebo with clinical management control. Results indicated that both person-specific effects and serial correlation play major roles in the longitudinal psychiatric response process. Ignoring either of these effects produces misleading estimates of uncertainty that form the basis of statistical tests of hypotheses.
Background
Adherence to the medical regimen after pediatric organ transplantation is important for maximizing good clinical outcomes. However, the literature provides inconsistent evidence regarding prevalence and risk factors for nonadherence posttransplant.
Methods
A total of 61 studies (30 kidney, 18 liver, 8 heart, 2 lung/heart-lung, and 3 with mixed recipient samples) were included in a meta-analysis. Average rates of nonadherence to 6 areas of the regimen, and correlations of potential risk factors with nonadherence, were calculated.
Results
Across all types of transplantation, nonadherence to clinic appointments and tests was most prevalent, at 12.9 cases per 100 patients per year (PPY). The immunosuppression nonadherence rate was 6 cases per 100 PPY. Nonadherence to substance use restrictions, diet, exercise and other healthcare requirements ranged from 0.6 to 8 cases per 100 PPY. Only the rate of nonadherence to clinic appointments and tests varied by transplant type: heart recipients had the lowest rate (4.6 cases per 100 PPY vs. 12.7–18.8 cases per 100 PPY in other recipients). Older age of the child, family functioning (greater parental distress, lower family cohesion), and the child’s psychological status (poorer behavioral functioning, greater distress) were among the psychosocial characteristics significantly correlated with poorer adherence. These correlations were small to modest in size (r =.12–.18).
Conclusions
These nonadherence rates provide benchmarks for clinicians to use to estimate patient risk. The identified psychosocial correlates of nonadherence are potential targets for intervention. Future studies should focus on improving the prediction of nonadherence risk and on testing interventions to reduce risk.
For patients receiving liver or other organ transplants for diseases associated with substance use, risk for relapse posttransplantation is a prominent clinical concern. However, there is little consensus regarding either the prevalence or risk factors for relapse to alcohol or illicit drug use in these patients. Moreover, the evidence is inconsistent as to whether patients with pretransplantation substance use histories show poorer posttransplantation medical adherence. We conducted a meta-analysis of studies published between 1983 and 2005 to estimate relapse rates, rates of nonadherence to the medical regimen, and the association of potential risk factors with these rates. The analysis included 54 studies (50 liver, 3 kidney, and 1 heart). Average alcohol relapse rates (examined only in liver studies) were 5.6 cases per 100 patients per year (PPY) for relapse to any alcohol use and 2.5 cases per 100 PPY for relapse with heavy alcohol use. Illicit drug relapse averaged 3.7 cases per 100 PPY, with a significantly lower rate in liver vs. other recipients (1.9 vs. 6.1 cases). Average rates in other areas (tobacco use, immunosuppressant and clinic appointment nonadherence) were 2 to 10 cases per 100 PPY. Risk factors could be examined only for relapse to any alcohol use. Demographics and most pretransplantation characteristics showed little correlation with relapse. Poorer social support, family alcohol history, and pretransplantation abstinence of Յ6 months showed small but significant associations with relapse (r ϭ 0.17-0.21). Future research should focus on improving the prediction of risk for substance use relapse, and on testing interventions to promote continued abstinence posttransplantation. Liver Transpl 14: 159-172, 2008.
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