background A longer duration of untreated psychosis (dup) is associated with a poorer clinical outcome in terms of: positive symptoms, relapse rate, and time to remission. However, the association between dup and negative symptoms is less consistent.
aim To understand if and to what extent dup and negative symptoms are correlated at various periods of follow-up. First we hypothesise that dup and negative symptoms are positively correlated even at long term follow-up, and second that patients with a shorter dup show more reduction of negative symptoms.
method Data of studies on first episode psychotic patients, published from December 1992 to March 2009 and reporting on dup and negative symptoms at baseline and at least one follow-up were included. To test our first hypothesis, we analysed individual patient data of each study using Spearman correlations. Then we calculated the summarised correlation for short- and long-term follow-up, using the aggregate data of each study in a Comprehensive Meta-Analysis (cma). To test our second hypothesis we used statistical software package stata.
results Of 402 papers which were analysed, 26 non-overlapping studies were selected. From 16 studies we obtained individual patient data with a total of 3339 patients. dup and negative symptoms are associated with all follow-up assessments up to eight years. Summarised correlations ranged between 0.114 at baseline and .226. Patients with shorter dup showed greater decline in negative symptoms at short-term follow-up (1-2 years) and also at long-term follow-up (5-8 years).
conclusion There is a strong and lasting positive relationship between dup and negative symptoms. Reducing dup might be the best option to ameliorate negative symptoms, since we do not have effective treatments yet. These findings support the efforts of early intervention teams, more research into the effects of early intervention on negative symptoms in the course of the illness is needed.