The original Prodromal Questionnaire (PQ) was created in 2005, and comprised of 92 yes/no questions. Over years with clinical and research use, this was subsequently refined too, two shorter versions the PQ-16 and the PQ-B. The PQ-16 is a 16 question questionnaire that is a self-report over the responder's lifetime. The PQ-16 is a good self-report screen for use in mental health care populations, partly due to the low number of questions which makes it quite practical for screening large help-seeking populations.

The PQ-16 was designed as a preliminary screening tool for “Ultra-High Risk (UHR) syndrome” also often called “attenuated psychosis syndrome”, which is a state when subthreshold psychotic experiences emerge. The idea was to use this questionnaire as a routine screening for psychosis risk, in a general help-seeking population. It was never designed to be used for diagnosis, grading severity, prognosis for monitoring treatment progress nor are there sufficient research studies that support its role other than a screening Questionnaire.

The PQ-16 can be scored by a sum of the distress scores (range 0-48), or the total number of symptoms endorsed (range 0-16). A cutoff score of 6 or more positively answered items on the symptom endorsement scale has been studied to be a good score for a positive screening. Research is widely varying on the optimal threshold, based on the population being studied. A total distress score threshold of ≥9 was supported, and in general mental health help-seeking populations a lower distress score cutoff of ≥8 was supported, along with symptom scores of ≥6 and ≥5 respectively. A cutoff of 6 or more symptoms on the PQ-16 has a true positive rate (87%) and high specificity (87%) in some research studies, and has the most supporting research.

Reference

Ising HK, Veling W, Loewy RL, et al. The validity of the 16-item version of the prodromal questionnaire (PQ-16) to screen for ultra high risk of developing psychosis in the general help-seeking population. Schizophrenia Bulletin 2012, 38 (6): 1288-96.

Savill M, D'Ambrosio J, Cannon TD, Loewy RL, et al. Psychosis risk screening in different populations using the Prodromal Questionnaire: A systematic review. Early Intervention in Psychiatry 2018, 12 (1): 3-14.

Suna, Wang L, Shi L, Zhao X, et al. Psychotic prodromal period questionnaire (PQ-16) to assess 4the risk of psychiatric students: Reliability and validity. Tongji University: Medicine Edition. 2015; 3:123-127.