Format

Send to

Choose Destination
Bipolar Disord. 2019 Aug 29. doi: 10.1111/bdi.12829. [Epub ahead of print]

An examination of the quality and performance of the Alda scale for classifying lithium response phenotypes.

Author information

1
Institute of Neuroscience, Newcastle University, Newcastle, UK.
2
Université Paris Diderot and INSERM UMRS1144, Paris, France.
3
Département de Psychiatrie et de Médecine Addictologique, AP-HP, GH Saint-Louis-Lariboisière-F. Widal, Paris, France.
4
Section of Psychiatry, Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.
5
Department of Pharmacology, Dalhousie University, Halifax, NS, Canada.
6
EPS Maison Blanche, Paris, France.
7
Institute of Psychiatric Phenomics and Genomics (IPPG), University Hospital, LMU Munich, Munich, Germany.
8
Department of Psychiatry, Dalhousie University, Halifax, NS, Canada.
9
National Institute of Mental Health, Klecany, Czech Republic.

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.

KEYWORDS:

Alda scale; clinical phenotypes; clinimetrics; genetics; lithium response; psychometrics

PMID:
31466131
DOI:
10.1111/bdi.12829

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center