Background. We sought to develop a clinically useful
subtyping system for the non-melancholic
depressive disorders, and here we assess one weighted to central aetiological
factors.
Methods. We studied 185 patients meeting DSM-III-R
and/or clinical criteria for non-melancholic
depression. Data were obtained by self-report, interview of patients and
from corroborative
witnesses. We developed a set of variables for class definition,
assessing: (i) ‘P’, disordered
personality as a vulnerability factor; (ii) ‘A’,
meeting criteria for a lifetime anxiety disorder or
positive on probe questions about trait anxiety characteristics,
so assessing anxiety as a vulnerability
factor; and (iii) ‘L’, psychiatrist and
consensually-rated life event stress prior to depression onset.
Results. A latent class analysis generated a four-class
solution for the P–A–L variables. Life event
stressors had similar item probabilities across all four classes,
and did not influence the four-class
‘P–A’ solution when deleted from the analysis,
suggesting that life event stress may act more as a
general provoking agent, rather than constituting any distinct
‘reactive’ or ‘situational’ depression
class. Three classes generated clinically meaningful groupings,
reflecting varying contributions of
anxiety and disordered personality functioning, and with evidence of
differential outcome over the following 12 months.
Conclusions: We suggest that a refined aetiologically-weighted
model may assist definition of the
non-melancholic depressive disorders, and provide the logic for exploring
the comparative utility of
differing treatments to identified vulnerability-based classes.