Concurrent validity of the Health of the Nation Outcome Scales compared with a patient-derived measure, the Symptom Checklist-90-Revised in out-patient clinics

Abstract

The psychometric properties of the Health of the Nation Outcome Scales (HoNOS) have been questioned. The present study examined the concurrent validity of the HoNOS against a patient-derived measure (the Symptom Checklist-90-R (SCL-90-R)) in out-patients. This relationship has previously only been investigated in in-patients. The study considered newly admitted patients, and only those with a complete data set were analyzed (N=118). Internal consistency (Cronbach's alpha) and effect sizes were calculated on pre- and post-treatment data. Concurrent validity was assessed using correlation (Spearman's rho) as well as agreement (kappa) on reliable and clinically significant change (RCSC). The internal consistencies associated with the SCL-90-R were satisfactory, a property shared only by the HoNOS sum score. The pre- to post-treatment changes in both instruments corresponded to medium to large effect sizes and were comparable in size. However, the correlations between the two were low, as was their agreement. This suggests that the HoNOS and the SCL-90-R measure somewhat different phenomena. The findings shed doubt on whether the patient-derived measures should be regarded as the “gold standard”. The instruments seem to complement each other.