Elsevier

Journal of Affective Disorders

Volume 240, November 2018, Pages 57-62
Journal of Affective Disorders

Research paper
Thresholds for severity, remission and recovery using the functioning assessment short test (FAST) in bipolar disorder

https://doi.org/10.1016/j.jad.2018.07.045Get rights and content

Highlights

  • Functional recovery has become one of the major challenges for patients living with bipolar disorder.

  • The lack of a consensus on the definition and appropriate tools to measure it hinders the development new interventions.

  • A classification of four categories has been proposed after comparing the FAST and the GAF-F.

  • Scores of 12, 20 and 40  in the FAST scale represent cut-offs for mild, moderate, and severe functional impairment.

Abstract

Background

Despite its importance, no distinction between none, mild, moderate and severe functional impairment is available. Categorization of functional impairment could help to better assess randomized controlled trials (RCT) and to study the correlates of functional impairment according to severity. The Functional Assessment Short Test (FAST) is one of the most widely used measures of functional impairment in bipolar disorder and related conditions, but to date no severity cut-offs have been determined for their use in clinical research and practice.

Method

FAST and Global Functioning Assessment (GAF) ratings from 65 euthymic outpatients with bipolar disorder at the Hospital Clínic in Barcelona were analyzed. A linear regression was computed using the FAST as the independent variable and the GAF as the dependent variable. Cut-offs scores for the FAST were estimated taking into account the GAF scores as a reference.

Results

Linear regression analysis with GAF scores as the dependent variable yielded the following equation: GAF score = 91,41–1,031 * FAST score. The cut-off scores for the FAST scale derived from this equation were as follows: scores from 0 to 11 included patients with no impairment. Scores from 12 to 20, represented the category of mild impairment. Moderate impairment comprised scores from 21 to 40. Finally, scores above 40 represent severe functional impairment. Further, the 4 × 4 cross-tabulation resulted in a significant association of FAST and GAF severity gradation: (Chi2= 95,095; df = 9; p < 0,001). Chance-corrected agreement was κ = 0,65 (p < 0.001).

Limitations

In the absence of a better alternative, the GAF, a broad clinical measure, was used as gold standard for establishing FAST categories according to severity.

Conclusion

The categorization of functional impairment in four categories based on empirical data shows that 12, 20 and 40 represent clinically meaningful cut-offs of the FAST for mild, moderate, and severe functional impairment and for functional recovery, remission, and improvement. The proposed categories are suitable to be further implemented in clinical studies and RCTs.

Introduction

Randomized controlled trials (RCTs) in psychiatry rely on clinician-rated instruments to study the treatment efficacy. Traditionally, the outcomes in RCTs have been defined in a context of reduction of symptoms (response/partial response/non response). However, in the last years, the focus has also moved from clinical remission to functional recovery (Vieta and Torrent, 2016). Hence, the most meaningful endpoint is no longer mere improvement, nor remission, but recovery. Indeed, functional recovery is, for some patients, a difficult goal, even if they have reached clinical remission. One of the major issues associated with functional recovery is the lack of consensus on the terminology and standards used to measure it (Harvey, 2006). Indeed, there exist many different tools to assess psychosocial functioning in psychiatry: the WHODAS 2.0 (WHO, 2001), now endorsed by the APA and the DSM-5 as the preferred measure of functional impairment (Garin et al., 2010, Ayuso-Mateos et al., 2013); the LIFE-RIFT (León et al., 1999) or the MSIF (Jaeger et al., 2003), among others. However, the FAST is the first scale that focuses on the principal problems faced by patients with Bipolar Disorder (BD) (Rosa et al., 2007). There is also a great heterogeneity in functional outcome when assessing patients with BD as reported in literature (Solé et al., 2018, MacQueen et al., 2001, Reinares et al., 2013). In this line, a recent study has classified the patients into different groups according to the impairment shown in different domains of functioning in the FAST scale by using an exploratory cluster analysis (Solé et al., 2018). Three different patterns were observed: one group with no significant impairment in any of the assessed domains; a second group with mild impairment in different domains but severe impairment in occupational functioning. Finally, the last group included patients with severe impairment in most of the assessed domains. The results of this study highlight the heterogeneity observed in functional outcome of patients suffering from BD, and the need to classify the degree of impairment more accurately. The categorization provided in that study is useful but it might not be the optimal way to measure severity in functional impairment, especially if the patients are enrolled in RCTs. Since RCT use total scores derived from observer rating scales (i.e.: Hamilton Depression Rating Scale (HAM-D) or Young Mania Rating Scale (YMRS), a severity gradation for functional outcome in BD is urgently needed. This classification is essential to assess the efficacy of new pharmacological and psychological treatments aiming at improving (direct or indirectly) psychosocial functioning.

The validation of the FAST scale in 2007 did not include cut-offs for severity gradation in psychosocial functioning (Rosa et al., 2007). A single cut-off was stablished to differentiate between impaired and non-impaired patients. Moreover, in that study, the concurrent validity of the FAST was studied considering the GAF-F. Given this previous experience with both scales, and that both the GAF-F (DSM-IV 4th edition, 1994) and the FAST assess functional outcome, it is important to analyze their empirical correlation and to establish corresponding cut-off values for severity gradations of the FAST scale (e.g: no impairment, mild, moderate, and severe) taking into account the GAF-F scores. Therefore, we analyzed data of GAF-F and FAST ratings from a sample of euthymic patients with bipolar I and II with the objective to establish different cut-off scores for the FAST scale.

Section snippets

Participants

Data for this analysis were pooled from a previous study assessing the validity of the FAST scale (Rosa et al., 2007). The original sample comprised a total of 101 patients with BD including both euthymic and acute patients that were recruited at the Hospital Clinic of Barcelona. In the original study, patients were interviewed with the Structured Clinical Interview for the DSM-IV TR criteria (First et al., 1997) and were administered several clinical and functional scales. Regarding

Demographic and clinical characteristics of the sample

A total of 65 patients out from the initial sample met the criteria of euthymia established for this analysis. The mean age of patients was 46 years old (SD = 13.5). Forty-six per cent of the total sample (n = 30) were female. Patients presented a mean of HAM-D score of 1.6 (S.D = 2.4) and a mean of YMRS total score of 0.6 (SD = 1.3). Approximately, one third of the sample (32.3%; n = 21) were married or living as a couple.

Patients presented a mean of 6 depressive episodes (Mean = 6.4;

Discussion

According to the present results we propose different cut-off values for the FAST scale in order to differentiate categories of severity of functional impairment:

  • a) No impairment: from 0 to 11 in the FAST total score. Patients in this category present good functioning in all areas, they live independently, they work and they have a meaningful social engagement. For patients who showed impaired functioning in the past, means recovery.

  • b) Mild impairment: from 12 to 20 in the FAST total score.

Role of funding source

This study was supported by the Instituto de Salud Carlos III, the CIBER of Mental Health (CIBERSAM), the Spanish Ministry of Economy, Industry and Competitiveness (PI15/00283, PI15/00330/PI16/00187) integrated into the Plan Nacional de I + D + I y cofinanciado por el ISCIII-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER).

Contributors

Rosa AR, Martínez-Arán A and Vieta E contributed to the design of the study and manuscript preparation.

Bonnín CM, Reinares M, Valentí M, Jimenez E and Solé B contributed to data analysis and manuscript preparation.

Montejo L contributed with literature review.

Conflicts of interest

Dr. Martinez-Arán has served as speaker or advisor for the following companies: Bristol-Myers Squibb, Otsuka, Lundbeck and Pfizer.

Dr. Vieta has received grants, CME-related honoraria, or consulting fees from AB-Biotics, Alexza, Almirall, Allergan, AstraZeneca, Bristol-Myers Squibb, Cephalon, Dainippon SumigtomoPharma, Eli Lilly, Ferrer, Forest Research Institute, Gedeon Richter, GlaxoSmith-Kline, Janssen, Janssen-Cilag, Jazz, Johnson & Johnson, Lundbeck, Merck, Novartis, Organon, Otsuka,

Acknowledgments

The authors would like to thank the support of the Spanish Ministry of Economy, Industry and Competitiveness; the CIBER of Mental Health (CIBERSAM); the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement (2017 SGR 1365) and the CERCA Programme / Generalitat de Catalunya. Finally, Dr. Bonnín would like to thank the Departament de Salut de la Generalitat de Catalunya for the PERIS grant (SLT002/16/00331).

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