Adherence to Treatment in Patients with Psychosis

Halfway during the 20th century, the development of antipsychotic medications revolutionised the care for patients with psychosis. Yet today, efficacy of antipsychotic medications is still far from perfect. Positive symptoms may persist despite antipsychotic treatment, the effects on cognitive and negative symptoms are small, and side-effects are often burdensome (Leucht et al., 2009a). Therefore, putting means and efforts into developing more efficacious medication, if possible with fewer side-effects, is to be applauded. However, effect-sizes of the second-generation antipsychotic medications on primary symptoms, in comparison to placebo, currently lie around. (Leucht et al., 2009b). Note that this effect-size is the result of a meta-analysis of controlled trials where medication intake was strictly monitored and adherence was probably high. However, in the average patient population, non-adherence is common in more than half of the patients (Perkins, 2002), and it is associated with poor outcome and high costs. In the UK for example, non-adherence to antipsychotic medication predicted an excess annual cost of more than 5.000 pound of service use per patient (Knapp et al., 2004), due to factors such as crisis interventions and readmissions. It is therefore plausible, considering that no recent development has improved the effects of antipsychotic medications substantially, that current intervention and research efforts are most likely to successfully improve outcome if they target the non-adherence problem. Medications, no matter how effective, are not helpful when patients do not use them. Given the fact that a mere 58% of the prescribed antipsychotic medications is actually taken by patients (Cramer & Rosenheck, 1998), solving the problem of non-adherence could theoretically almost double the efficacy of antipsychotic treatment in everyday practice.

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