Validation of the Brazilian version of the neurological fatigue index for multiple sclerosis

Lopes, Josiane; Lavado, Edson Lopes; Kaimen-Maciel, Damacio Ramón

doi:10.1590/0004-282X20160030

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Arquivos de Neuro-Psiquiatria

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Articles • Arq. Neuro-Psiquiatr. 74 (4) • Apr 2016 • https://doi.org/10.1590/0004-282X20160030 copy

Validation of the Brazilian version of the neurological fatigue index for multiple sclerosis

Validação da versão brasileira do índice neurológico de fadiga na esclerose múltipla

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The Neurological Fatigue Index for Multiple Sclerosis (NFI-MS) is a new fatigue assessment instrument. The aim of this study was to cross-culturally adapt and assess the psychometric properties of the Brazilian version of the NFI-MS (NFI-MS/BR).

Method

Two hundred and forty subjects with MS were recruited for this study. The adaptation of the NFI-MS was performed by translation and back translation methodology. In psychometric analysis was performed the administration of the questionnaires Epworth Sleep Scale, Fatigue Severity Scale, Modified Fatigue Impact Scale, Multiple Sclerosis Impact Scale-29, NFI-MS/BR and Pittsburgh Sleep Quality Index with retest of the NFI-MS/BR after 7 days.

Results

Reliability was assessed (intraclass correlation coefficients between 0.77 and 0.86), and validity by testing 41 hypotheses about expected correlations between subscales and confirmed 36. The majority of correlations were demonstrated.

Conclusion

The NFI-MS/BR is a cross-culturally adapted, valid, and reliable instrument for assessing MS fatigue among Brazilian subjects.

multiple sclerosis; fatigue; assessment; validation studies; psychometrics

Variable	Adaptation sample (n = 30)	Validation sample (n = 210)
Age (years)
Median (IQR)	42.5 (28–51.5)	39 (29–50)
Gender n (%)
Female	24 (80)	160 (76.1)
Male	6 (20)	50 (23.8)
Ethnicity n (%)
Caucasian	26 (86.6)	158 (75.2)
Non-Caucasian	4 (13.3)	52 (24.7)
Education n (%)
Incomplete elementary	0 (0)	12 (5.7)
Elementary	10 (33.3)	36 (17.1)
High School	10 (33.3)	78 (37.1)
Higher education	10 (33.3)	84 (40.0)
Years since diagnosis (years)
Median (IQR)	8.6 (5.3–10.9)	5.25 (2.25–9.95)
Age at diagnosis (years)
Median (IQR)	30.5 (23.7–42)	31 (24.5–41.5)
MS clinical form n (%)
Relapsing remitting	24 (80)	171 (81.4)
Secondary progressive	5 (16.6)	16 (7.6)
Clinically isolated	1 (3.3)	14 (6.6)
Primary progressive	0 (0)	6 (2.8)
Not defined	0 (0)	3 (1.4)
EDSS
Median (IQR)	3 (1.75–4)	3 (1–4)
*Fatigue n (%)	-	136 (75.5)

Instruments	Scale range	Median (IQR)
NFI-MS-BR
Summary	0–30	19 (11.5–23)
Physical	0–24	15 (9–19)
Cognitive	0–12	6 (3–9)
Diurnal Sleep	0–18	10 (7–12)
Nocturnal Sleep	0–15	8 (5–11)
Total	0–69	40 (26.5–49)
FSS	9–63	41 (27–52)
MFIS
Physical	0–36	11 (7–17)
Cognitive	0–40	7 (2–13.5)
Total	0–84	22 (12–32.5)
MSIS-29
Physical	0–100	20 (9–37)
Psychological	0–45	8 (4–15)
Total	0–145	30 (13–51)
ESS	0–24	5 (2–10)
PSQUI	0–21	5 (3–9)
EDSS	0–10	3 (1–4)

NFI-MS/BR (sub)scale	ICC	[95%CI]	SEM agreement	Bland-Altman			95%LC

				d	95%CI of`d	SD of`d
Summary
Intra-observer	0.83	[0.74–0.89]	2.2	-0.81	-2.34–0.71	3.24	-10.91–7.64
Interobserver	0.79	[0.71–0.86]	1.7	0.88	-2.67–2.82	3.31	-8.44–10.67
Physical
Intra-observer	0.86	[0.77–0.93]	1.3	-0.83	-1.37–2.41	4.30	-12.03–9.11
Interobserver	0.84	[0.74–0.91]	1.4	0.87	-0.57–2.25	3.80	-9.27–11.03
Cognitive
Intra-observer	0.82	[0.73–0.95]	2.5	-0.80	-2.39–0.71	3.47	-10.33–7.65
Interobserver	0.77	[0.72–0.90]	2.1	0.76	-0.31–2.27	2.87	-8.41–9.73
Diurnal sleep and rest
Intra-observer	0.87	[0.83–0.94]	1.1	-0.57	-2.10–0.63	2.33	-11.07–9.32
Interobserver	0.85	[0.75–0.92]	1.0	0.54	-0.30–2.27	3.10	-7.43–18.34
Nocturnal sleep and sleppiness
Intra-observer	0.85	[0.81–0.97]	1.8	-0.62	-1.45–2.18	3.32	-11.13–9.67
Interobserver	0.82	[0.75–0.86]	1.4	0.80	-0.47–2.15	2.41	-9.30–12.12

			NFI-MS/BR (rho )

INSTRUMENTS	Total	Summary	Physical	Cognitive	Diurnal Sleep	Nocturnal Sleep
Subscales	Total	Summary	Physical	Cognitive	Diurnal Sleep	Nocturnal Sleep
Summary	0.92	-	-	-	-	-
NFI-MS Physical	0.90	0.96	-	-	-	-
NFI-MS Cognitive	0.82	0.86	0.72	-	-	-
NFI-MS Diurnal Sleep	0.65	0.46	0.45	0.38	-	-
NFI-MS Nocturnal Sleep	0.79	0.60	0.58	0.56	0.45	-
MFIS Physical	0.73	0.74	0.78	0.55	0.41	0.52
MFIS Cognitive	0.59	0.59	0.50	0.76	0.29	0.43
MFIS Psychosocial	0.64	0.65	0.67	0.58	0.34	0.45
FSS	0.69	0.71	0.76	0.59	0.43	0.45
MSIS-29 Physical	0.73	0.75	0.76	0.59	0.38	0.53
MSIS-29 Psychological	0.59	0.53	0.50	0.78	0.27	0.51
ESS	0.33	0.21	0.26	0.25	0.35*	0.36*
PSQUI	0.58	0.52	0.53	0.42	0.35*	0.56*
EDSS	0.48	0.53	0.56	0.35	0.28	0.25

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[1] Correspondence: Josiane Lopes; Avenida Inglaterra, 155; 86046-000 Londrina PR, Brasil; E-mail: josianelopes@yahoo.com.br