Validity of a ‘proxy’ for the deficit syndrome derived from the Positive And Negative Syndrome Scale (PANSS)

Abstract

Schizophrenia patients with the deficit syndrome (DS) may represent a homogeneous subgroup. To increase the practicability of diagnosing the DS, Kirkpatrick et al. (Kirkpatrick, B., Buchanan, RW., Breier, A. Carpenter, WT., 1993. Case identification and stability of the deficit syndrome of schizophrenia. Psychiatry Research 47,[47][48][49][50][51][52][53][54][55][56] proposed the use of a 'proxy' case identification tool using standardized symptom ratings instead of the Schedule for the Deficit Syndrome (SDS) which requires an independent clinical assessment. The Proxy for the Deficit Syndrome (PDS) is based on the extraction of symptoms that are essentially equivalent or overlap substantially with the restricted affect and diminished emotional range on the SDS. Kirkpatrick et al. (1993) reported good sensitivity and specificity in a comparison of SDS and PDS assessments among 100 chronic schizophrenia outpatients. The present investigation involves the comparison of the deficit syndrome as assessed by the "gold standard" Schedule for the Deficit Syndrome with the ratings of the same symptoms embodied in the "proxy instrument" the PANSS, within the same group of 156 inpatients.Forty-four patients were assessed by the SDS to have the deficit syndrome. Patients with and without the DS, as defined by the SDS, did not differ for age, education, age at illness onset and duration of illness. The two main 'proxy' measures PDS1 and PDS2 discriminated across the SDS groups. The direct dichotomous comparison of the actual SDS and the 'proxy' derived PDS groups demonstrated good specificity (78.6% and 79.5%) and moderate to very good sensitivity (61.4% and 86.4%) and there was a moderately low rate of false positive cases (21.4% and 20.5%). For the two main 'proxy' measures (PDS1 & PDS2) kappas were .38 and .59, representing poor to good agreement.In our sample of rigorously diagnosed schizophrenia inpatients, the use of a 'proxy' case identification tool for the deficit syndrome would appear to be a viable alternative in identifying a subgroup of schizophrenia patients with the deficit syndrome when the use of the actual SDS is

The mechanism of life-threatening water imbalance in schizophrenia and its relationship to the underlying psychiatric illness

“…Furthermore, deficits in social function in laboratory animals induced by diverse pharmacologic or environmental factors are normalized with oxytocin treatment (Lee et al, 2005; Lee et al, 2007), and are at least partly mediated by the ventral striatum (Ross and Young, in press), a brain region closely linked to psychosis. Social dysfunction, as noted, is a key feature of schizophrenia, reflected in the prominence of negative symptoms and the deficit syndrome (Addington et al, 2006; Goetz et al, 2007; Kirkpatrick et al, 2001; Kirkpatrick, 1997). Together these observations suggest that diminished CNS oxytocin activity could contribute to the social dysfunction in schizophrenia.…”

Primary and persistent negative symptoms: Concepts, assessments and neurobiological bases

“…The PDS has been used in several investigations aimed at characterizing DS (Kirkpatrick et al, 1996a(Kirkpatrick et al, , 2002Messias and Kirkpatrick, 2001;Subotnik et al, 2000Subotnik et al, , 1998Tek et al, 2001;Cohen and Docherty, 2004;Goetz et al, 2007;Strauss et al, 2010). Later on, a proxy measure was derived from the Positive and Negative Syndrome Scale (PANSS) and demonstrated good specificity (78.6%-79.5%) and moderate to very good sensitivity (61.4%-86.4%) (Goetz et al, 2007). However, concerns were raised about the temporal stability and external validity of the proxy measures and caution when employing the PDS in future research is suggested (Subotnik et al, 1998;Roy et al, 2001a;Cohen et al, 2010).…”

Further Neuroimaging Evidence for the Deficit Subtype of Schizophrenia

“…The proxy for the deficit syndrome has good specificity, sensitivity, and accuracy for identification of patients with deficit schizophrenia 28 in both early-episode and chronic populations. [30][31][32][33][34][35] Specifically, the proxy for the deficit syndrome is defined as the sum of the scores from either the Positive and Negative Syndrome Scale or the Brief Psychiatric Rating Scale of the anxiety, guilt feelings, depressive mood, and hostility items subtracted from the blunted affect item score. This calculation reflects the lack of negative affect and lack of dysphoria that are characteristic of patients with defi-rect classification, patients with nondeficit schizophrenia were identified as those who ranked in the bottom quartile of deficit scores in each sample.…”