Diagnostic accuracy of the Gerontological Personality Disorder Scale (GPS) in Dutch general practice

Personality disorders (PDs) often remain unrecognized in older adults by doctors in general practice. Therefore, this study evaluated the diagnostic accuracy of a screening instrument, the Gerontological Personality Disorder Scale (GPS), in a Dutch general-practice population of older adults.

The psychometric properties of the GPS patient (GPS-pv) and informant (GPS-iv) versions were assessed in a sample of 302 (144 male) patients (average age: 69.9 years) and 302 (124 male) informants (average age: 64.7 years), respectively, using an informant-based personality questionnaire (the Hetero-Anamnestische Persoonlijkheidsvragenlijst ) as a reference criterion.

The internal consistency (average item correlation) of the subscale and total scores of the GPS-pv and GPS-iv were .12 (HAB), .16 (BIO), and .10 (total); and .16 (HAB), .15 (BIO), and .12 (total), respectively. The test--retest reliability was strong for both the GPS-pv (rs = .56 [HAB], rs = .67 [BIO], rs = .66 [total]) and the GPS-iv (rs = .52 [HAB], rs = .65 [BIO], rs = .68 [total]) versions. The sensitivity and specificity of the GPS-pv were .83 and .27, respectively, with a cutoff score of ≥1. Raising the cutoff score to ≥2, the sensitivity dropped to .59, whereas the specificity rose to .57. For the GPS-iv, a cutoff score of ≥3 maximized the sensitivity (.78) and specificity (.65).

The diagnostic accuracy of the GPS-iv was preferable to that of the GPS-pv. This is the first psychometric study to use the GPS as an age-specific screening instrument for PDs.