Reduction in movement-evoked pain and fatigue during initial 30-minute transcutaneous electrical nerve stimulation treatment predicts transcutaneous electrical nerve stimulation responders in women with fibromyalgia.

ABSTRACT: We previously showed that 1 month of transcutaneous electrical nerve stimulation (TENS) reduces movement-evoked pain and fatigue in women with fibromyalgia (FM). Using data from this study (Fibromyalgia Activity Study with TENS [FAST]), we performed a responder analysis to identify predictors of clinical improvement in pain and fatigue with TENS, validated these models using receiver operator characteristic, and determined number needed to treat and number needed to harm. Participants were randomly assigned to active-TENS (2-125 Hz; highest-tolerable intensity), placebo-TENS, or no-TENS for 1 month. At the end of the randomized phase, placebo-TENS and no-TENS groups received active-TENS for 1 month. The predictor model was developed using data from the randomized phase for the active-TENS group (n = 103) and validated using data from placebo-TENS and no-TENS groups after active-TENS for 1 month (n = 155). Participant characteristics, initial response to TENS for pain and fatigue, sleep, psychological factors, and function were screened for association with changes in pain or fatigue using a logistic regression model. Predictors of clinical improvement in pain were initial response to pain and widespread pain index (area under the curve was 0.80; 95% confidence interval: 0.73-0.87). Predictors of clinical improvement in fatigue were marital status, sleep impairment, and initial response to TENS (area under the curve was 0.67; 95% confidence interval: 0.58-0.75). Number needed to treat for pain and fatigue ranged between 3.3 and 5.3. Number needed to harm ranged from 20 to 100 for minor TENS-related adverse events. The response to an initial 30-minute TENS treatment predicts who responds to longer-term TENS use in women with FM, making this a clinically useful procedure. Number needed to treat and number needed to harm suggest that TENS is effective and safe for managing pain and fatigue in FM.

Transcutaneous Electrical Nerve Stimulation Reduces Movement-Evoked Pain and Fatigue: A Randomized, Controlled Trial.

OBJECTIVE: Fibromyalgia (FM) is characterized by pain and fatigue, particularly during physical activity. Transcutaneous electrical nerve stimulation (TENS) activates endogenous pain inhibitory mechanisms. This study was undertaken to investigate if using TENS during activity would improve movement-evoked pain and other patient-reported outcomes in women with FM. METHODS: Participants were randomly assigned to receive active TENS (n = 103), placebo TENS (n = 99), or no TENS (n = 99) and instructed to use it at home during activity 2 hours each day for 4 weeks. TENS was applied to the lumbar and cervicothoracic regions using a modulated frequency (2-125 Hz) at the highest tolerable intensity. Participants rated movement-evoked pain (primary outcome measure) and fatigue on an 11-point scale before and during application of TENS. The primary outcome measure and secondary patient-reported outcomes were assessed at baseline (time of randomization) and at 4 weeks. RESULTS: After 4 weeks, a greater reduction in movement-evoked pain was reported in the active TENS group versus the placebo TENS group (group mean difference -1.0 [95% confidence interval -1.8, -0.2]; P = 0.008) and versus the no TENS group (group mean difference -1.8 [95% confidence interval -2.6, -1.0]; P < 0.0001). A reduction in movement-evoked fatigue was also reported in the active TENS group versus the placebo TENS group (group mean difference -1.4 [95% confidence interval -2.4, -0.4]; P = 0.001) and versus the no TENS group (group mean difference -1.9 [95% confidence interval -2.9, -0.9]; P = <0.0001). A greater percentage of the patients in the active TENS group reported improvement on the global impression of change compared to the placebo TENS group (70% versus 31%; P < 0.0001) and the no TENS group (9%; P < 0.0001). There were no TENS-related serious adverse events, and <5% of participants experienced minor adverse events from TENS. CONCLUSION: Among women who had FM and were on a stable medication regimen, 4 weeks of active TENS use compared to placebo TENS or no TENS resulted in a significant improvement in movement-evoked pain and other clinical outcomes. Further research is needed to examine effectiveness in a real-world setting to establish the clinical importance of these findings.

Physical activity is related to function and fatigue but not pain in women with fibromyalgia: baseline analyses from the Fibromyalgia Activity Study with TENS (FAST).

BACKGROUND: Although exercise is an effective treatment for fibromyalgia, the relationships between lifestyle physical activity and multiple symptomology domains of fibromyalgia are not clear. Thus, the purpose of this study was to comprehensively examine the relationships between lifestyle physical activity with multiple outcome domains in women with fibromyalgia, including pain, fatigue, function, pain-related psychological constructs, and quality of life. METHODS: Women (N = 171), aged 20 to 70 years, diagnosed with fibromyalgia, recruited from an ongoing two-site clinical trial were included in this prespecified subgroup analysis of baseline data. Physical activity was assessed using self-report and accelerometry. Symptomology was assessed using questionnaires of perceived physical function, quality of life, fatigue, pain intensity and interference, disease impact, pain catastrophizing, and fear of movement. In addition, quantitative sensory testing of pain sensitivity and performance-based physical function were assessed. Correlation coefficients, regression analyses and between-group differences in symptomology by activity level were assessed, controlling for age and body mass index (BMI). RESULTS: Lifestyle physical activity was most closely associated with select measures of physical function and fatigue, regardless of age and BMI. Those who performed the lowest levels of lifestyle physical activity had poorer functional outcomes and greater fatigue than those with higher physical activity participation. No relationships between lifestyle physical activity and pain, pain sensitivity, or pain-related psychological constructs were observed. CONCLUSIONS: Lifestyle physical activity is not equally related to all aspects of fibromyalgia symptomology. Lifestyle physical activity levels have the strongest correlations with function, physical quality of life, and movement fatigue in women with fibromyalgia. No relationships between lifestyle physical activity and pain, pain sensitivity, or psychological constructs were observed. These data suggest that physical activity levels are more likely to affect function and fatigue, but have negligible relationships with pain and pain-related psychological constructs, in women with fibromyalgia. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01888640 . Registered on 28 June 2013.

Reliability and Construct Validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) Instruments in Women with Fibromyalgia.

OBJECTIVE: The Patient-Reported Outcomes Measurement Information System (PROMIS) was developed to standardize measurement of clinically relevant patient-reported outcomes. This study evaluated the reliability and construct validity of select PROMIS static short-form (SF) instruments in women with fibromyalgia. DESIGN: Analysis of baseline data from the Fibromyalgia Activity Study with TENS (FAST), a randomized controlled trial of the efficacy of transcutaneous electrical nerve stimulation. SETTING: Dual site, university-based outpatient clinics. SUBJECTS: Women aged 20 to 67 years diagnosed with fibromyalgia. METHODS: Participants completed the Revised Fibromyalgia Impact Questionnaire (FIQR) and 10 PROMIS static SF instruments. Internal consistency was calculated using Cronbach alpha. Convergent validity was examined against the FIQR using Pearson correlation and multiple regression analysis. RESULTS: PROMIS static SF instruments had fair to high internal consistency (Cronbach α = 0.58 to 0.94, P < 0.05). PROMIS 'physical function' domain score was highly correlated with FIQR 'function' score (r = -0.73). The PROMIS 'total' score was highly correlated with the FIQR total score (r = -0.72). Correlations with FIQR total score of each of the three PROMIS domain scores were r = -0.65 for 'physical function,' r = -0.63 for 'global,' and r = -0.57 for 'symptom' domain. PROMIS 'physical function,' 'global,' and 'symptom' scores explained 58% of the FIQR total score variance. CONCLUSIONS: Select PROMIS static SF instruments demonstrate convergent validity with the FIQR, a legacy measure of fibromyalgia disease severity. These results highlight the potential utility of select PROMIS static SFs for assessment and tracking of patient-reported outcomes in fibromyalgia.

Perceived function and physical performance are associated with pain and fatigue in women with fibromyalgia.

BACKGROUND: Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue and associated with significant impairment in perceived function and reduced physical performance. The purpose of this study was to determine the degree to which pain and fatigue are associated with perceived function and physical performance in women with fibromyalgia. METHODS: Hierarchical linear regression determined the contribution of pain and fatigue (Numeric Rating Scale (NRS) for resting, movement and combined) to perceived function (Fibromyalgia Impact Questionnaire Revised - Function Subscale, FIQR-Function), Multidimensional Assessment of Fatigue - Activities of Daily Living (MAF-ADL) and SF-36 Physical Function Subscale (SF-36-PF) and physical performance (6-Minute Walk Test, 6MWT and Five Time Sit To Stand, 5TSTS) while controlling for age, body mass index, pain catastrophizing, fear of movement, anxiety, and depression in women with fibromyalgia (N = 94). RESULTS: For perceived function, movement pain and movement fatigue together better predicted FIQR-function (adjusted R(2) = 0.42, p ≤ 0.001); MAF-ADL (adjusted R(2) = 0.41, p ≤ 0.001); and SF-36-PF function (adjusted R(2) = 0.34, p ≤ 0.001). For physical performance measures, movement pain and fatigue together predicted 6MWT distance (adjusted R(2) = 0.42, p ≤ 0.001) and movement fatigue alone predicted performance time on the 5TSTS (adjusted R(2) = 0.20, p ≤ 0.001). CONCLUSIONS: Pain and fatigue are significantly associated with and explain more than one-third of the variance in perceived function and physical performance in women with fibromyalgia. TRIAL REGISTRATION: NIH Clinicaltrials.gov REGISTRATION: NCT01888640 . Registered 13 June 2013.