Several retrospective analyses have examined the interplay between the duration of untreated illness and subsequent treatment effectiveness in patients with schizophrenia.[Owens et al., 2010; Primavera et al., 2012]
One study reanalysed the data from the Northwick Park Study of First Episodes in the context of duration of untreated illness, finding a correlation between the duration of untreated illness and relapse rates.[Owens et al., 2010] Another study analysed clinical records of a cohort of 80 patients with schizophrenia, tabulating outcome variables such as number of hospitalisations, attempted suicide, course of illness, and GAF (Global Assessment of Functioning) scores.[Primavera et al., 2012] A shorter duration of untreated psychosis was linked to favourable course of illness, even in the very long term.[Primavera et al., 2012]
References:
Owens DC, Johnstone EC, Miller P, et al. Duration of untreated illness and outcome in schizophrenia: test of predictions in relation to relapse risk. Br J Psychiatry 2010; 196 (4): 296–301.
Primavera D, Bandecchi C, Lepori T, et al. Does duration of untreated psychosis predict very long term outcome of schizophrenic disorders? Results of a retrospective study. Ann Gen Psychiatry 2012; 11 (1): 21.