Reliability of the Italian version of the Brief (21-item) Prodromal Questionnaire (IPQ-B) for psychosis risk screening in a young help-seeking population

I. Scazza 1, L. Pelizza 1, S. Azzali 1, F. Paterlini 1, S. Garlassi 1, L.R. Chiri 2, M. Poletti 1, F. Fontana 1, R. Favazzo 1, S.V. Barbanti 1, M. Fabiani 1, L. Pensieri 1, L. Cioncolini 1, E. Semrov 1, A. Raballo 3 4

1 Department of Mental Health and Pathological Addiction, Reggio Emilia Public Health Care Centre, Reggio Emilia, Italy; 2 Department of Mental Health and Pathological Addiction, Bologna Public Health Care Centre, Bologna, Italy; 3 Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway; 4 Department of Medicine, Division of Psychiatry, Clinical Psychology and Rehabilitation, University of Perugia, Italy

Objective

Among current screeners for psychosis-risk mental states, the Prodromal Questionnaire-Brief (21 items) (PQ-B) is used. We aimed to assess reliability of the Italian version of the PQ-B in a young help-seeking sample. Methods – We included 151 individuals, aged 13-35 years, seeking help at the Reggio Emilia outpatient mental health services in a large semirural catchment area (550.000 inhabitants). Participants completed the Italian version of the PQ-B (iPQ-B) and were subsequently evaluated with the Comprehensive Assessment of At-Risk Mental States (CAARMS). We examined test-retest reliability, internal consistency and diagnostic accuracy (i.e. sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios) between PQ-B and CAARMS UHR-defined criteria using coefficient of stability (k), Cronbach’s alpha and Cohen’s kappa, respectively.

Results

The iPQ-B showed excellent short term test-retest reliability (k = 0.891), high internal consistency (α = 0.876) and acceptable diagnostic accuracy (sensitivity = 91.4% at the proposed cut-off of ≥ 6 on total distress score).

Conclusions

Psychometric properties of the iPQ-B were satisfactory. The iPQ-B is a suitable screening tool for routine use in mental health care services. Indeed, it is short and therefore easy to implement in routine assessment of early psychosis.

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