A “healthy living” intervention focused on exercise and diet has failed to impact body mass index (BMI) in overweight people with psychosis when evaluated in the setting of a randomised controlled trial.
The INTERACT study found that changes in BMI and waist circumference over a 12-month period were not significantly different between people assigned to the intervention and those given usual care.
INTERACT (INTERvention to Encourage ACTivity, Improve Diet, and Reduce Weight Gain) included 105 patients diagnosed with schizophrenia, schizophreniform disorder, schizoaffective disorder, delusional disorder, brief reactive psychosis or psychosis not otherwise specified.
They were randomly assigned to receive the intervention plus treatment as usual or just treatment as usual.
The intervention drew on Leevanthal’s Common Sense Model and had both motivational and behavioural components. Participants received seven individual psychoeducation sessions over a 6-month period, followed by a booster session, and were offered access to activities such as football, walking, cycling and cooking. They also received written information and advice.
Compliance with the intervention was good, with low attrition, report Karina Lovell (University of Manchester, UK) and fellow authors in the Journal of Clinical Psychiatry.
Between baseline and 12 months, BMI fell by 0.31 kg/m2 in the intervention group and was unchanged in the usual care group, a nonsignificant difference. Changes in waist circumference at 6 and 12 months were also not different between the groups.
Exploratory analysis suggested that the effect may have been greater among patients taking atypical antipsychotics at the time of randomization. In this subgroup, BMI decreased by 0.23 kg/m2 in the intervention group and increased by 1.22 kg/m2 in control patients; this difference was still not statistically significant, however.
Furthermore, a multivariate analysis identified just one baseline characteristic that significantly correlated with change in BMI – namely, higher depression scores predicted a greater reduction in BMI.
In discussing the reasons for the failure of their intervention, the researchers say that BMI may not have been the most appropriate outcome measure. They add: “Future research might consider additional measures of cardiovascular vulnerability such as high-density lipoprotein—low-density lipoprotein cholesterol ratio and levels of triglycerides.”
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