An examination of the quality and performance of the Alda scale for classifying lithium response phenotypes
Journal
Bipolar Disorders
Journal Volume
22
Journal Issue
3
Pages
255-265
Date Issued
2020
Author(s)
Etain, Bruno
Manchia, Mirko
Brichant-Petitjean, Clara
Geoffroy, Pierre A
Schulze, Thomas
Alda, Martin
Bellivier, Frank
Amare A.
Ardau R.
Backlund L.
Baune B.
Barboza A.
Benabarre A.
Chaumette B.
Chillotti C.
Clark S.
Colom F.
Del Zompo M.
Dalkner N.
Dantas C.
Ferentinos P.
Garnham J.
Jamain S.
Jimenez E.
Khan J.-P.
Kuo P.
Lavebratt C.
Maj M.
Millischer V.
Monteleone P.
Pisanu C.
Potash J.
Reif A.
Reininghaus E.
Schalling M.
Schofield P.
Schubert K.
Severino G.
Slaney C.
Smith D.
Squassina A.
Tondo L.
Vieta E.
Witt S.
ConLiGen collaborators
Abstract
OBJECTIVES: The Retrospective Assessment of the Lithium Response Phenotype Scale (Alda scale) is the most widely used clinical measure of lithium response phenotypes. We assess its performance against recommended psychometric and clinimetric standards. METHODS: We used data from the Consortium for Lithium Genetics and a French study of lithium response phenotypes (combined sample >2500) to assess reproducibility, responsiveness, validity, and interpretability of the A scale (assessing change in illness activity), the B scale, and its items (assessing confounders of response) and the previously established response categories derived from the Total Score for the Alda scale. RESULTS: The key findings are that the B scale is vulnerable to error measurement. For example, some items contribute little to overall performance of the Alda scale (eg, B2) and that the B scale does not reliably assess a single construct (uncertainty in response). Machine learning models indicate that it may be more useful to employ an algorithm for combining the ratings of individual B items in a sequence that clarifies the noise to signal ratio instead of using a composite score. CONCLUSIONS: This study highlights three important topics. First, empirical approaches can help determine which aspects of the performance of any scale can be improved. Second, the B scale of the Alda is best applied as a multidimensional index (identifying several independent confounders of the assessment of response). Third, an integrated science approach to precision psychiatry is vital, otherwise phenotypic misclassifications will undermine the reliability and validity of findings from genetics and biomarker studies.
Publisher
Blackwell Publishing Inc.
Type
journal article