The Cronholm-Ottosson Depression Scale: the first depression scale designed to rate changes during treatment

In 1960 Ottosson published the first specific depression rating scale (the Cronholm-Ottosson Depression Scale) designed to be sensitive in measuring change during antidepressive therapy. Ottosson and his group have never used factor analysis to validate the scale, as the items of the scale were used factor analysis to validate the scale, as the items of the scale were selected on a preconceived idea for homogeneity, i.e. having a monotonic correspondence to the underlying dimension of severity of depression. The most appropriate method of testing the construct validity of the Cronholm-Ottosson Depression Scale is latent structure analysis. Using the original Ottosson data, a latent structure analysis has been made showing that the 8 items of the scale are homogeneously related, i.e. can be ordered on one dimension of severity of depression. The descriptive statistic of a 50% reduction of pretreatment score (or more) equaled the global clinical score of moderate to excellent improvement. Both scales showed that, already after 4 electroconvulsive treatments, about 80% of depressed patients who received adequate fits had moderate to excellent improvement, whereas only around 40% of depressed patients who received inadequate fits improved moderately or excellently.