Validity of the ALS-Depression-Inventory (ADI-12)— A new screening instrument for depressive disorders in patients with amyotrophic lateral sclerosis

Eva Maria Hammera, , , Sonja Häckera, Martin Hautzingerb, Thomas D. Meyerc and Andrea Küblera, d
aDepartment of Medical Psychology and Behavioral Neurobiology, Eberhard-Karls-University Tübingen, Gartenstraße 29, 72074 Tübingen, Germany
bDepartment of Psychology, University Tübingen, Tübingen, Germany
cSchool of Neurology, Neurobiology & Psychiatry, Newcastle University, United Kingdom
dClinical and Health Psychology Research Centre, School of Human and Life Sciences, Roehampton University, London, United Kingdom
Received 7 August 2007; revised 28 November 2007; accepted 28 November 2007. Available online 11 February 2008.



Abstract
Background
Depressive symptoms among patients with amyotrophic lateral sclerosis (ALS) are usually measured with conventional questionnaires. These measurements do not consider the specific circumstances of the underlying disease. The purpose of this study was to assess the validity of a new short 12 items ALS-Depression-Inventory (ADI-12). We determined convergent, criterion, and concurrent validity. The Structured Clinical Interview (SCID) for DSM-IV was used as the gold standard and the Beck Depression Inventory (BDI) and the WHO Well Being Index (WHO-5) to assess concurrent validity.

Methods
A total of 39 ALS patients in all stages of the disease were interviewed. Convergent validity was estimated by the inter-correlation between the ADI-12 and the BDI. Criterion and concurrent validity were specified with respect to sensitivity, specificity and predictive values. Receiver Operating Characteristics (ROC) and Areas Under the Curves (AUC) were calculated.

Results
All three depression scales showed excellent internal consistencies (Cronbach's α: .8–.9). The correlation between the ADI-12 and the BDI was high (r = .80). For the ADI-12 a cut-off of ≥ 30 (SE = 100%, SP = 83%) identified all patients with a current episode of major depression. A more liberal cut-off (≥ 23) identified all patients with any depressive disorder including minor depression at the cost of specificity (60%).

Conclusions
With the ADI-12 ALS patients with depressive disorders can be reliably identified. We recommend the ADI-12 for routine screening in primary care of ALS patients.

Keywords: Amyotrophic lateral sclerosis; Depression; ALS-Depression-Inventory; Screening; Validity


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