Adherence therapy improves symptoms in patients with schizophrenia but does not appear to affect adherence, treatment attitudes. or functioning, according to results of a randomized controlled trial.
"We observed a small effect of AT [adherence therapy] on patient symptoms but not adherence, treatment attitudes, or functioning following an acute episode of schizophrenia," wrote Dr. Michael Schulz of the University of Applied Sciences, Bielefeld, Germany, and his colleagues. "It was disappointing that we found no evidence to support our proposed mechanism of action for AT; there was no evidence of an effect of the intervention on either patients’ beliefs or adherence."
The parallel-group trial involved 161 patients admitted for treatment of an acute exacerbation of schizophrenia – 123 of whom finished the trial – and randomized patients to receive either eight sessions of adherence therapy or treatment as usual (Schizophr. Res. 2013;146:59-63).
Outcomes were assessed with the positive and negative syndrome scale (PANSS) and serum concentration to dose ratio, with researchers suggesting this was the first such trial to use a biological marker to measure adherence.
The adherence therapy consisted of eight one-on-one sessions with a trained therapist, designed to explore, assess, and test patients’ history, experience, and beliefs about medication and treatment. Treatment as usual followed national guidelines.
Previous studies of adherence therapy had produced mixed results, although trials that intervened just after an acute episode generally had more positive outcomes.
"We hypothesized that AT initiated whilst patients with schizophrenia are inpatient and followed up in the community will be effective in enhancing adherence and reducing psychopathology compared to usual care," the researchers wrote.
The authors suggested that the lack of clear benefit in adherence or patient beliefs pointed to a "ceiling effect," particularly as there was likely a sample bias toward more compliant patients with almost half the patients eligible for recruitment to the trial either refusing to take part or being excluded.
"A major problem in conducting adherence trials in severe mental illness is recruiting nonadherent patients," the researchers reported. "Both AT and TAU [treatment as usual] groups were not only adherent to treatment, which might be expected in inpatients following an acute episode, but also had positive medication attitudes. This may explain why AT has so little effect on patients’ beliefs, i.e. there may be a ceiling effect limiting the possible impact AT could have."
Despite the failure of this and previous trials to demonstrate clear benefits of adherence therapy on patient adherence and beliefs, the authors said the approach was still "theoretically sound."
"The findings from this trial would lend weight to the argument that intervening as soon as possible after an acute episode of illness in patients with schizophrenia affords the best chance to effect change," they wrote.
"Perhaps one of the most important challenges in adherence research is the recruitment of patients who are treatment non-compliant."
The study was supported by AstraZeneca, and one author declared honoraria and consultancies to a range of pharmaceutical companies, including AstraZeneca.