Fatigue in Parkinson's disease: Metric properties of the fatigue impact scale for daily use (D-FIS), and its impact on quality of life

OBJECTIVE

In Parkinson's disease patients, fatigue is a disabling non-motor symptom whose prevalence ranges from 28% to 58%. The Fatigue Impact Scale for Daily Use (D-FIS), one of the various scales for quantifying fatigue. The aim of our study was to analyze the metric properties of the D-FIS in PD subjects and assess the impact of fatigue on their quality of life.

PATIENTS AND METHODS

The cohort in this study was comprised of 211 consecutive patients with a PD diagnosis regularly followed up at the Movement Disorders Unit of the Neurology Department at Carlos Andrade Marín Hospital (HCAM) in Quito, Ecuador, according to the United Kingdom PD Society Brain Bank criteria. Data Quality, Acceptability, Reliability, Stability (test-retest), Validity and Multiple linear regression analysis were determined.

RESULTS

The final sample consisted of 138 men (65.4%) and 73 women. Forty-six percent of these (98 patients) were in stage II of H&Y. We obtained a Cronbach's α value of 0.912 and an ICC value of 0.79. D-FIS was strongly correlated with depression (Spearman rho [Srho] 0.60), anxiety (Srho 0.59), quality of life (Srho 0.67), and non-motor symptoms (Srho 0.66). The scale's discriminant validity, assessed among the different stages of H&Y by the Kruskal-Wallis test, showed major significance (X² = 23.183, p ≤ 0.001). In the Multiple linear regression study, the resulting model proves that fatigue has a determining effect on quality of life.

CONCLUSIONS

The D-FIS has good metric properties and demonstrates that fatigue significantly affects PD patients' quality of life and that its impact is independent from that of anxiety, depression, and sleep disorders.

Validation of Fatigue Impact Scale with various item sets - a Rasch analysis

PURPOSE

Fatigue is a symptom in patients with chronic gastrointestinal (GI) and liver diseases. Different instruments have been developed to assess the severity of fatigue and the 40-item Fatigue Impact Scale (FIS) is among the most widely used. Shorter versions of FIS include the 21-item Modified Fatigue Impact Scale (MFIS), and an eight-item version for everyday use. The study aimed to assess construct validity, reliability, and sufficiency of the raw score of the original FIS with 40 items, and examine the sufficiency of the 21 items from the Modified scale and the eight items of the Daily Fatigue Impact Scale (D-FIS), all of which are embedded in the 40-item scale.

METHODS

Patients with chronic GI or liver disease (n = 354) completed the FIS with 40 items. The majority (57%) was under the age of 55 years and approximately half were females (48%). Various item sets of FIS were derived which showed fit to the Rasch model.

RESULTS

Local dependency and multidimensionality in FIS and the 21-item Modified scale were resolved with a testlet solution but the D-FIS showed local dependency and multidimensionality and differential item functioning (DIF) still remained. Two new item sets fulfilling unidimensionality and no DIF are suggested, one with 15 items and a six-item scale for daily use. The transformation table shows score-interval scale estimates for all these item sets.

CONCLUSIONS

Both the FIS and the Modified scale can be used to measure fatigue albeit requiring some adjustment for DIF. The eight-item D-FIS is more problematic, and its summed score is not valid. Alternative 15- and 6-item versions presented in this paper can offer valid summed scores, and the transformation table allows transformation of raw scores and comparisons across all versions. Implications for rehabilitation The Fatigue Impact Scale and the Modified Fatigue Impact Scale can be used to measure fatigue after adjustments for differential item functioning. Alternative 15- and 6-item versions of Fatigue Impact Scale offer valid summed scores. The summed score for the Daily Fatigue Impact Scale is not valid. A transformation table with raw scores and Rasch transformed interval scale metric makes it possible to compare scores derived from the Fatigue Impact Scale, the Modified Fatigue Impact Scale and the proposed 15- and 6-item versions of Fatigue Impact Scale for research and/or clinical use.

No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates

BACKGROUND & AIMS

Patients with non-celiac gluten sensitivity (NCGS) do not have celiac disease but their symptoms improve when they are placed on gluten-free diets. We investigated the specific effects of gluten after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates (fermentable, oligo-, di-, monosaccharides, and polyols [FODMAPs]) in subjects believed to have NCGS.

METHODS

We performed a double-blind cross-over trial of 37 subjects (aged 24-61 y, 6 men) with NCGS and irritable bowel syndrome (based on Rome III criteria), but not celiac disease. Participants were randomly assigned to groups given a 2-week diet of reduced FODMAPs, and were then placed on high-gluten (16 g gluten/d), low-gluten (2 g gluten/d and 14 g whey protein/d), or control (16 g whey protein/d) diets for 1 week, followed by a washout period of at least 2 weeks. We assessed serum and fecal markers of intestinal inflammation/injury and immune activation, and indices of fatigue. Twenty-two participants then crossed over to groups given gluten (16 g/d), whey (16 g/d), or control (no additional protein) diets for 3 days. Symptoms were evaluated by visual analogue scales.

RESULTS

In all participants, gastrointestinal symptoms consistently and significantly improved during reduced FODMAP intake, but significantly worsened to a similar degree when their diets included gluten or whey protein. Gluten-specific effects were observed in only 8% of participants. There were no diet-specific changes in any biomarker. During the 3-day rechallenge, participants' symptoms increased by similar levels among groups. Gluten-specific gastrointestinal effects were not reproduced. An order effect was observed.

CONCLUSIONS

In a placebo-controlled, cross-over rechallenge study, we found no evidence of specific or dose-dependent effects of gluten in patients with NCGS placed diets low in FODMAPs.

No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates

BACKGROUND & AIMS

Patients with non-celiac gluten sensitivity (NCGS) do not have celiac disease but their symptoms improve when they are placed on gluten-free diets. We investigated the specific effects of gluten after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates (fermentable, oligo-, di-, monosaccharides, and polyols [FODMAPs]) in subjects believed to have NCGS.

METHODS

We performed a double-blind cross-over trial of 37 subjects (aged 24-61 y, 6 men) with NCGS and irritable bowel syndrome (based on Rome III criteria), but not celiac disease. Participants were randomly assigned to groups given a 2-week diet of reduced FODMAPs, and were then placed on high-gluten (16 g gluten/d), low-gluten (2 g gluten/d and 14 g whey protein/d), or control (16 g whey protein/d) diets for 1 week, followed by a washout period of at least 2 weeks. We assessed serum and fecal markers of intestinal inflammation/injury and immune activation, and indices of fatigue. Twenty-two participants then crossed over to groups given gluten (16 g/d), whey (16 g/d), or control (no additional protein) diets for 3 days. Symptoms were evaluated by visual analogue scales.

RESULTS

In all participants, gastrointestinal symptoms consistently and significantly improved during reduced FODMAP intake, but significantly worsened to a similar degree when their diets included gluten or whey protein. Gluten-specific effects were observed in only 8% of participants. There were no diet-specific changes in any biomarker. During the 3-day rechallenge, participants' symptoms increased by similar levels among groups. Gluten-specific gastrointestinal effects were not reproduced. An order effect was observed.

CONCLUSIONS

In a placebo-controlled, cross-over rechallenge study, we found no evidence of specific or dose-dependent effects of gluten in patients with NCGS placed diets low in FODMAPs.