Depressive dimensions and item response analysis of the Hamilton Depression Rating Scale-17 in eating disorders

Evaluation of Computerized Adaptive Tests (CATs) for longitudinal monitoring of depression, anxiety, and stress reactions

BACKGROUND

Computerized adaptive testing (CAT) based on Item Response Theory, (IRT) offers an efficient way for accurate measurement of patient reported outcomes. The efficiency lies within a minimal response burden and a high measurement precision over a broad measurement range. The objective of the study was to evaluate and compare the responsiveness of CATs measuring anxiety, depression, and stress reaction to standard static self-assessment tools.

METHODS

Longitudinal data of n=595 psychosomatic inpatients were analyzed for evaluating retest-reliability and sensitivity to change of the CATs compared to static measures (GAD-7, PHQ-9, and PSQ) using correlational and ANOVA statistics. The study hypothesized that CATs are at least as retest-reliable and as sensitive to change as static tools.

RESULTS

The three CATs show a low burden for patients, administering on average 5-7 (±2-6SD) items with similar retest-reliability compared to the static tools applied (A-CAT: r=.78 vs. GAD-7: r=.75, D-CAT: r=.71 vs. PHQ-9: r=.75, S-CAT: r=.80 vs. PSQworries scale: r=.80). The CATs were overall as sensitive to change as the static tools (Cohen׳s d ranged between .19 and .69).

LIMITATIONS

This is a monocenter, observational, longitudinal study without external clinical criteria; thus generalization to other settings may be limited.

CONCLUSIONS

The tested CATs belong to the first generation of CATs being used in daily routine for more than a decade. They are as retest reliable and sensitive to change as static tools. Newer CATs may provide further practical advantages.

Toronto alexithymia scale for patients with eating disorder: [corrected] performance using the non-parametric item response theory

BACKGROUND

The aim of this study was to investigate the performance of the Toronto Alexithymia Scale (TAS-20) in patients with eating disorders. As a secondary objective, we analyzed a subset of items in order to determine whether the total score is a good tool for classifying these patients and whether the items are ordered according to the difficulty of choosing a particular answer depending on the severity of the patient's condition.

SUBJECTS AND METHODS

We administered the TAS-20 to 103 consecutive patients who met DSM-IV-R criteria for anorexia nervosa, bulimia nervosa, or eating disorders not otherwise specified. Mokken scale analysis, nonparametric item response theory (NIRT), and confirmatory factor analysis (CFA) were used to test the psychometric properties of the scale. To improve our understanding of the structure underlying the TAS-20, we used an automated item selection procedure based on the Mokken scale.

RESULTS

We identified a subset of 13 independent and clinically interpretable items that are potentially sufficient to rate patients with alexithymia. This subset was considered a unidimensional reduction of the TAS-20. However, the scale composed of this subset needs to be validated. Thirteen of the 20 items were maximally related to alexithymia because they have a one-dimensional structure. The NIRT and CFA enabled us to identify a maximal subset of items that conform to the requirements for good measurement of alexithymia in patients with eating disorders.