Functioning pre- and post-treatment in schizophrenia; further investigations into lead time bias and duration of untreated psychosis.

OBJECTIVE

The association between duration of untreated psychosis (DUP) and later outcome is not fully understood. Jonas et al. in their 20-year follow-up found that the association could be explained by lead-time bias. In this study we aimed to analyze the relationship between DUP, time since onset of psychosis and functional outcome using a similar statistical approach as the Jonas study.

METHOD

Using data from 496 participants with first-episode schizophrenia, DUP was assessed using the IRAOS and functioning at the baseline assessment and the subsequent follow-ups (1, 2, 5 and 10 years) was assessed using the GAF-F. For premorbid functioning, the Premorbid Assessment of Functioning Scale was used and rescaled to correspond to the GAF.

RESULTS

The model with the best fit of data included both a slope and a level change. This model of level of function over time had the inflection point at the time of first treatment. This model indicated a slow decline per year until first treatment, at which point there was a sharp decrease in functioning, and after which functioning gradually improved again. Both in this model and in models accounting for potential lead-time bias, however, longer DUP was associated with a decrease in function for each additional week of DUP. This is in contrast with the Jonas et al. study.

CONCLUSION

In this study, we did not find evidence of a lead-time bias, but rather found that onset of treatment occurs at the time when participants level of functioning was most impaired, and consequently was not at random.