The Development, Validity and Reliability of Psychotic Symptoms Rating Scale for Patients with Schizophrenia (Prasrimahabhodi Assessment Schizophrenia Scale: PASS8)
Thoranin Kongsuk MD1, Kamonnet Wannasewok MD2, Jetsada Thongtao MD1, Supattra Konkhamdee MNS1, Kadsaraporn Kenbubpha MSc (Epidemiology)1, Teerapa Thanee MEd1, Jirungkoon Nuttharungsri MEd3
Affiliation : 1 Prasrimahabhodi Psychiatric Hospital, Department of Mental Health, Ministry of Public Health, Nonthaburi, Thailand 2 Department of Psychiatry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand 3 Faculty of Nursing, Ratchathani University, Ubon Ratchathani, Thailand
Objective : To develop and test the validity and reliability of PASS8-a psychotic symptoms rating scale for the assessment
of patients with schizophrenia which was designed for use in primary or secondary health care units.
Materials and Methods : The present study consisted of 2 stages. The first stage involved the development of psychotic
symptoms rating scale; it composed of 8 items, 3 dimensions, and 5-point severity rating scales. In the second stage, a cross-
sectional study was conducted to test the validity and reliability of PASS8 in patients with schizophrenia who were treated
at Prasrimahabhodi Psychiatric Hospital. The patients were diagnosed with schizophrenia according to ICD-10 or DSM-IV
diagnostic criteria and varied in phase of treatment; acute, stabilization and stable. The total of 150 volunteers aged 18 years
and older were interviewed by psychiatric nurses using PASS8 before the patients were evaluated by psychiatrists with
CGI-SCH. Data analysis was done by calculating Cronbach ‘s alpha coefficient, Pearson’s correlation coefficient (r),
sensitivity, specificity, and likelihood ratio of cut-off point categorized level of symptoms severity according to assessment
by using PASS8
Results : Out of the total of 150 participants, they were predominantly single male between the ages of 31 to 40 years old.
More than half of volunteers had an income of less than 1,000 baht a month and lived in Ubon Ratchathani Province with their
parents. After performing a statistical analysis, the Cronbach’s alpha indicated acceptable internal consistency. When
comparing between PASS8’s range of score categorized according to the severity of the symptoms and symptoms of patients
with schizophrenia assessed by 2 psychiatrists using CGI-SCH, Pearson’s correlation coefficient (r) was 0.741 (p-value
<0.001). This test showed that sensitivity, specificity, and likelihood ratio in mild severity level were 64%, 64% and 1.78
(0.38 to 0.85), respectively, in moderate severity level were 37%, 67 % and 1.11 (0.65 to 1.91), respectively, and in severe
severity level were 75%, 93% and 11.25 (2.84 to 244.64), respectively. The mean duration of completing this rating scale was
6.0 minutes (SD 2.6). Minimum and maximum duration were 2.0 minutes and 14.0 minutes, respectively.
Conclusion : PASS8 had acceptable internal consistency and statistic results indicated good correlation with CGI-SCH. It
contained high sensitivity and specificity in separating schizophrenic patients with high severity and was adequate for
evaluating patients with mild severity. It had low sensitivity in detection that was moderately severe. It used for evaluation
of psychotic symptoms in patients with schizophrenia in short duration by trained primary/secondary health care provider.
Keywords : Psychotic symptoms rating scale, Schizophrenia, Validity, Reliability
