Based on their ability to identify patients diagnosed with clinical depression or anxiety, scores on each of the subtests of the HADS were classified as follows: 0 to7 were considered non-cases, 8-10 was considered doubtful, and ratings of 11-21 were considered definite cases. The reliability of this classification was then tested on the next 50 patients. To test the validity of these scores for an indication of the severity of depression and anxiety, Spearman correlations were calculated. Results were r =0.70 for depression and r = 0.74, significant at the P< 0.001 level. To determine whether the anxiety and depression subscales detected different aspects of mood, patients were selected that were considered to have a distinct difference by interview assessment. When compared to subjects self-rated scores, anxiety scores had an r = +0.54, P<0.05 and depression had an r = +0.79, P<0.01. The authors concluded that this scale has also been shown to be a valid measure of the severity of depression and anxiety.
The HADS was used in a study (Al-Shammari, Khoja & Al-Sabaie, 1993) to compare physicians’ perceptions of anxiety and depression, and patient self report of anxiety and depression on the HADS. The physicians diagnosed fewer cases of anxiety and depression than the HADS. The authors describe the HADS to be superior to physician clinical judgment for screening clinically significant anxiety and depression in many of the patients, as the incidence seen in their sample population using the HADS was close to that expected when compared to the incidence of anxiety and depression in other developing countries.
