Due to an error in data coding, tables 1–3 are replaced by the following. The Corrigendum Note below each table explains the error and correction.

Table 1. Concordance between laboratory drug tests and self-rated assessments of drug use in schizophrenia patients (N = 1042)

NPV, Negative predictive value: probability of (−) laboratory drug tests and (−) self-rated assessments; PPV, positive predictive value: probability of (+) laboratory drug tests and (+) self-rated assessments; SENS, sensitivity: proportion of (+) laboratory drug tests and (+) self-rated assessments; SPEC, specificity: proportion of (−) laboratory drug tests and (−) self-rated assessments; ‘Any use’ indicates the use of cocaine, cannabis or methamphetamine; laboratory drug test (+/−) includes urine drug test results and radioimmunoassay (RIA) of hair test results.

Corrigendum Note . The findings presented in this updated version of Table 1 are not qualitatively different from the results that were previously reported in error. This updated version of Table 1 shows 28% of the overall sample tested (+) for any drug use, and drug use under-reporting was observed for 44% of the participants with (+) laboratory drug tests.

Table 2. Comparative characteristics of schizophrenia patients who under-reported and accurately reported their illicit drug use

PANSS, Positive and Negative Syndrome Scale; ITAQ, Insight and Treatment Attitudes Questionnaire; S.D., standard deviation; CPZ, chlorpromazine equivalent dose (CPZ daily dose equivalents were computed based on prescribed typical and/or atypical antipsychotic medications).

Corrigendum Note. As indicated in this updated version of Table 2, a greater proportion of women under-reported drug use as compared to men, but this finding is now a trend and is not significant at conventional thresholds. The other findings that are reported in this version of Table 2 are not qualitatively different than the results that were previously reported in error.

Table 3. Predictors of under-reporting of illicit drug use among schizophrenia patients

PANSS, Positive and Negative Syndrome Scale, S.E., standard error; OR, odds ratio.

^a OR represents a 10-year change in age.

Corrigendum Note. Compared to the results that were previously reported, the findings reported in this updated version of Table 3 suggest that positive symptomatology is a significant predictor of the under-reporting of cannabis use. The updated results also indicate that age is a significant predictor of the under-reporting of cocaine use. There are no other qualitative differences of mention between this version of Table 3 and the results that were previously reported in error.