Fatigue in Sarcoidosis - Treatment With Methylphenidate

Sarcoidosis and fatigue

Sarcoidosis is a systemic granulomatous disease that affects all ethnic groups and ages. In the United Kingdom the incidence of the disease is 5.0 cases per 100,000 patient years, with a mean age at diagnosis of 47 years, frequently affecting patients of working age(Gribbin et al). The cause is unknown and there is no cure(Iannuzzi et al). Many patients suffer from debilitating fatigue for which there is presently no treatment.

Fatigue has been described as a "core symptom" of sarcoidosis, and is present in up to 80% of patients(Marcellis et al). A "post-sarcoidosis chronic-fatigue syndrome" has been described(James), denoting the presence of fatigue where there is no evidence of active disease. The presence of this symptom has been shown to adversely affect quality of life(Michielsen et al). Although there increased risk of obstructive sleep apnoea and sleep-disordered breathing occurring in sarcoidosis patients(Michielsen et al; Drent et al) the majority of patients have no identifiable cause for fatigue other than their sarcoidosis.

Both the British Thoracic Society(Bradley et al) and American Thoracic Society(Costabel et al) produce guidelines for physicians treating people with sarcoidosis. Neither guideline gives any advice on treatment of fatigue. Fatigue is a common problem in sarcoidosis. In a study of 76 patients with sarcoidosis, 50.7% reported pathological levels of fatigue, defined as a Fatigue Assessment Scale (FAS) score of greater than 21 units, compared with 8.6% of controls. People reporting fatigue scores above 21, had poorer EuroQoL Visual Analogue Scale (EQVAS) scores compared with people reporting fatigue scores of 21 or below (mean scores 0.561 vs 0.792 , p<0.001) (Unpublished data, Norfolk and Norwich University Hospital). This shows that fatigue impacts upon quality of life in sarcoidosis.

Methylphenidate - a treatment for fatigue

Methylphenidate (and its isomer dexmethylphenidate), which is used to treat attention deficit hyperactivity disorder(Keating et al), is an amphetamine-derivative which works by amplifying dopamine signals through inhibition of dopamine reuptake and enhancement of extracellular dopamine in the basal ganglia(Volkow et al). It has been used to treat fatigue in other settings with good effect. In a placebo-controlled, double-blind trial in post-chemotherapy participants with fatigue, methylphenidate exhibited a clinically significant reduction in fatigue(Lower et al). Prior to the results from this trial, a Cochrane review of treatments for cancer-related fatigue from 5 RCTs had shown an improvement in fatigue through methylphenidate treatment, leading them to conclude "the current evidence supports the use of psychostimulants in cancer-related fatigue"(Minton et al). Another trial investigated methylphenidate for the treatment of fatigue in 109 HIV-positive patients over a 6-week period. Methylphenidate improved fatigue on a visual analogue scale, with a 26.2 point increase (maximum of 100) from baseline, with 41% of participants receiving the drug demonstrating a greater than 50% improvement in visual analogue scale score(Breitbart et al). In contrast, no difference between methylphenidate and placebo was seen in a cohort of 68 fatigued patients who had received radiotherapy for brain tumours followed over a 12 week period(Butler et al).

In the case of sarcoidosis, so far only one small study has investigated the use of dexmethylphenidate for fatigue(Lower et al). Ten patients were included in this double blind crossover trial. Participants reported clinically and statistically significant improvements in fatigue measured by both the FAS and the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) score after 8 weeks of treatment, although no statistically significant improvement was seen in six minute walk distance (6MWD) compared with placebo. The drug was well tolerated; all participants completed the study and no significant increase in side effects was noted between the patients receiving placebo and dexmethylphenidate.

Rationale for current study

Prior to designing a definitive study, issues about the feasibility of undertaking a sufficiently large trial require to be resolved. Completed trials have only used methylphenidate for 8-12 weeks, so sustainability of effect, tolerability of medications over a long period and retention of participants within the trial are unknown. Whilst the use of medications such as methylphenidate may not be used on a continuous basis in the clinical setting, their use on a 6-12 month basis may not be unreasonable, hence the need to review the effect of the medication over a longer period. Furthermore, it is unclear how many people would be willing to participate in a longer trial , and how many potential participants would be suitable for enrolment using our present inclusion and exclusion criteria. For this reason, a feasibility trial is necessary before committing to a larger trial.

In addition, this trial will evaluate exercise and activity through both a modified shuttle walk test (MSWT) and accelerometer-measured change in activity levels. Although methylphenidate has not been shown to significantly improve 6MWD(Lower et al), a larger study using a more responsive test may be required to evaluate exercise capacity in this setting. This could be because as a self-paced test it is a sub-maximal exercise test - this has been shown to be the case in a study of interstitial lung disease (ILD) patients (including sarcoidosis) where peak oxygen uptake, carbon dioxide uptake and ventilation were all lower during 6MWD than on cardiopulmonary exercise testing(Holland et al). By not reaching their maximum exercise level this may make the test less responsive to change. This is particularly relevant given that the ILD cohort who did not reach maximal exercise or oxygen uptake during their 6MWD were likely to be much more limited in cardiopulmonary function than the cohort anticipated to be enrolled in a study of treatment of fatigue and therefore much more likely to get closer to their peak oxygen uptake during a 6MWD. Given that activity levels measured by accelerometers in people with sarcoidosis is related to fatigue (Korenromp et al), this trial will evaluate the feasibility of using them as an outcome measure in a clinical trial, including whether participants will wear the devices for long enough (i.e. 4 days out of 7, at least 10 hours per day) to get valid data for estimating daily activity levels.

Study Design

This is a parallel-arm RCT including 30 participants, randomised on a 1.5:1 basis in favour of the active treatment arm (18 participants will receive methylphenidate, 12 will receive placebo). The rationale of this trial is to determine the feasibility of designing and performing a sufficiently large RCT in the future looking for proof of clinical effect of methylphenidate in the treatment of sarcoidosis-associated fatigue. As a result, this study is not powered to detect a clinical difference in a clinical outcome, although these will be measured and analysed (the estimate of effect size will be used for future power calculations). Therefore the primary outcomes regard feasibility and safety, not treatment effect (see Outcome Measures section).

Participants will receive either methylphenidate or placebo for 24 weeks, with a further assessment performed 6 weeks after completion of the trial. They will be carefully monitored over the initial 6 weeks to ensure that they are stable on the drug - during this time they will be seen every 2 weeks (at 0,2,4 and 6 weeks). Following this period they will be seen less frequently (at 12 and 24 weeks, with postal questionnaires performed at 18 weeks) to detect sustainability of effect. Determining if treatment effect is sustained over the second half of the trial period will help to establish how long any future trial will need to be. Although each participant is required to attend frequent visits to the hospital, this trial has been designed in conjunction with sarcoidosis patients and ensures that participant safety is paramount.