Magnesium supplementation for the treatment of restless legs syndrome and periodic limb movement disorder: A systematic review

Magnesium supplementation is often suggested for restless legs syndrome (RLS) or period limb movement disorder (PLMD) based on anecdotal evidence that it relieves symptoms and because it is also commonly recommended for leg cramps. We aimed to review all articles reporting the effects of magnesium supplementation on changes in RLS and/or PLMD. We conducted a systematic search looking for all relevant articles and then two reviewers read all article titles and abstracts to identify relevant studies. Eligible studies were scored for their quality as interventional trials. We found 855 abstracts and 16 of these could not be definitively excluded for not addressing all aspects of our research question. Seven full-text articles were unlocatable and one was ineligible which left eight studies with relevant data. One was a randomised placebo-controlled trial, three were case series and four were case studies. The RCT did not find a significant treatment effect of magnesium but may have been underpowered. After quality appraisal and synthesis of the evidence we were unable to make a conclusion as to the effectiveness of magnesium for RLS/PLMD. It is not clear whether magnesium helps relieve RLS or PLMD or in which patient groups any benefit might be seen.

Physician Decision Making and Clinical Outcomes With Laboratory Polysomnography or Limited-Channel Sleep Studies for Obstructive Sleep Apnea: A Randomized Trial

BACKGROUND

The clinical utility of limited-channel sleep studies (which are increasingly conducted at home) versus laboratory polysomnography (PSG) for diagnosing obstructive sleep apnea (OSA) is unclear.

OBJECTIVE

To compare patient outcomes after PSG versus limited-channel studies.

DESIGN

Multicenter, randomized, noninferiority study. (Australian New Zealand Clinical Trials Registry: ACTRN12611000926932).

SETTING

7 academic sleep centers.

PARTICIPANTS

Patients (n = 406) aged 25 to 80 years with suspected OSA.

INTERVENTION

Sleep study information disclosed to sleep physicians comprised level 1 (L1) PSG data (n = 135); level 3 (L3), which included airflow, thoracoabdominal bands, body position, electrocardiography, and oxygen saturation (n = 136); or level 4 (L4), which included oxygen saturation and heart rate (n = 135).

MEASUREMENTS

The primary outcome was change in Functional Outcomes of Sleep Questionnaire (FOSQ) score at 4 months. Secondary outcomes included the Epworth Sleepiness Scale (ESS), the Sleep Apnea Symptoms Questionnaire (SASQ), continuous positive airway pressure (CPAP) compliance, and physician decision making.

RESULTS

Change in FOSQ score was not inferior for L3 (mean difference [MD], 0.01 [95% CI, -0.47 to 0.49; P = 0.96]) or L4 (MD, -0.46 [CI, -0.94 to 0.02; P = 0.058]) versus L1 (noninferiority margin [NIM], -1.0). Compared with L1, change in ESS score was not inferior for L3 (MD, 0.08 [CI, -0.98 to 1.13; P = 0.89]) but was inconclusive for L4 (MD, 1.30 [CI, 0.26 to 2.35; P = 0.015]) (NIM, 2.0). For L4 versus L1, there was less improvement in SASQ score (-17.8 vs. -24.7; P = 0.018), less CPAP use (4.5 vs. 5.3 hours per night; P = 0.04), and lower physician diagnostic confidence (P = 0.003).

LIMITATION

Limited-channel studies were simulated by extracting laboratory PSG data and were not done in the home.

CONCLUSION

The results support manually scored L3 testing in routine practice. Poorer outcomes with L4 testing may relate, in part, to reduced physician confidence.

PRIMARY FUNDING SOURCE

National Health and Medical Research Council and Repat Foundation.

Glycopyrronium once-daily significantly improves lung function and health status when combined with salmeterol/fluticasone in patients with COPD: the GLISTEN study, a randomised controlled trial

BACKGROUND

The optimal use of various therapeutic combinations for moderate/severe chronic obstructive pulmonary disease (COPD) is unclear. The GLISTEN trial compared the efficacy of two long-acting anti-muscarinic antagonists (LAMA), when combined with an inhaled corticosteroid (ICS) and a long-acting β2 agonist (LABA).

METHODS

This randomised, blinded, placebo-controlled trial in moderate/severe COPD patients compared once-daily glycopyrronium (GLY) 50 µg, once-daily tiotropium (TIO) 18 µg or placebo (PLA), when combined with salmeterol/fluticasone propionate (SAL/FP) 50/500 µg twice daily. The primary objective was to determine the non-inferiority of GLY+SAL/FP versus TIO+SAL/FP on trough FEV1 after 12 weeks. An important secondary objective was whether addition of GLY to SAL/FP was better than SAL/FP alone.

RESULTS

773 patients (mean FEV1 57.2% predicted) were randomised; 84.9% completed the trial. At week 12, GLY+SAL/FP demonstrated non-inferiority to TIO+SAL/FP for trough FEV1: least square mean treatment difference (LSMdiff) -7 mL (SE 17.4) with a lower limit for non-inferiority of -60 mL. There was significant increase in week 12 trough FEV1 with GLY+SAL/FP versus PLA+SAL/FP (LSMdiff 101 mL, p<0.001). At 12 weeks, GLY+SAL/FP produced significant improvement in St George's Respiratory Questionnaire total score versus PLA+SAL/FP (LSMdiff -2.154, p=0.02). GLY+SAL/FP demonstrated significant rescue medication reduction versus PLA+SAL/FP (LSMdiff -0.72 puffs/day, p<0.001). Serious adverse events were similar for GLY+SAL/FP, TIO+SAL/FP and PLA+SAL/FP with an incidence of 5.8%, 8.5% and 5.8%, respectively.

CONCLUSIONS

GLY+SAL/FP showed comparable improvements in lung function, health status and rescue medication to TIO+SAL/FP. Importantly, addition of GLY to SAL/FP demonstrated significant improvements in lung function, health status and rescue medication compared to SAL/FP.

TRIAL REGISTRATION NUMBER

NCT01513460.

Marked reduction in obstructive sleep apnea severity in slow wave sleep

INTRODUCTION

Obstructive sleep apnea (OSA) is widely accepted to improve during slow wave sleep (SWS) compared to lighter stages of NREM sleep. However, supporting data to establish the magnitude and prevalence of this effect is lacking. Consequently, we examined this phenomenon, controlling for posture, in a large group of patients investigated for OSA at an academic clinical sleep service.

METHODS

A detailed retrospective analysis was conducted on data obtained from each 30-sec epoch of sleep in 253 consecutive full-night diagnostic polysomnography studies performed over a 3-month period. Respiratory and arousal event rates were calculated within each stage of sleep, in the supine and lateral postures, and across the whole night, with OSA patients classified on the basis of an overall apnea-hypopnea index (AHI) > or =15 events/h. Central sleep apnea (CSA) patients were defined by a central apnea index > 5/h. Sleep latency and time, and respiratory and arousal event rates in OSA, CSA, and non-OSA patients were compared between sleep stages and postures using linear mixed model analysis. The numbers of patients achieving reduced event rates in SWS and in the lateral posture were also examined.

RESULTS

There were 171 patients with OSA, 14 with CSA, and 68 non-OSA patients. OSA patients took significantly longer to achieve slow wave and REM sleep (p < 0.001) than non-OSA patients and had less stage 4 sleep (p = 0.037). There were striking improvements in AHI and arousal index (Al) from stage 1 to 4 NREM sleep (p <0.001), with intermediate levels in REM sleep. AHI and Al were also markedly reduced in lateral versus supine sleep in all sleep stages (p < 0.001), with an effect size comparable to that of the slow wave sleep effect. The majority of OSA patients achieved low respiratory event rates in SWS. Eighty-two percent of patients achieved an AHI <15 and 57% < 5 events/hour during stage 4 sleep.

CONCLUSION

Although OSA patients demonstrate both a delayed and reduced proportion of SWS compared to non-OSA subjects, once they achieved SWS, AHI, and Al markedly improved in most patients.

Upper airway function and arousability to ventilatory challenge in slow wave versus stage 2 sleep in obstructive sleep apnoea

Patients with obstructive sleep apnoea (OSA) have reduced event rates during slow wave sleep (SWS) compared with stage 2 sleep. To explore this phenomenon, ventilatory and arousal timing responses to partial and complete airflow obstruction during SWS versus stage 2 sleep were examined.

METHODS

Ten patients, mean+/-SD apnoea-hypopnoea index (AHI) 49.7+/-16.5 events/h with reduced OSA frequency during SWS (SWS AHI 18.9+/-14.0 events/h) slept with an epiglottic pressure catheter and nasal mask/pneumotachograph. Patients underwent rapid continuous positive airway pressure (CPAP) dialdowns to three subtherapeutic levels and brief airway occlusions in random order.

RESULTS

Post-dialdown, there were marked reductions in peak flow and minute ventilation, and progressive increases in inspiratory effort (p<0.001), but with limited ventilatory recovery and no differences between sleep stages. CPAP versus peak flow relationships on the third and second to last breath pre-arousal were not different between sleep stages. Arousals occurred later and post-dialdown arousal probability was lower during SWS compared with stage 2 sleep, Cox hazard ratio (95% CI) 0.65 (0.48 to 0.88), p=0.006. During SWS occlusions, time to arousal (mean+/-SEM) was prolonged (23.0+/-2.6 vs 17.1+/-1.7 s, p=0.02). Inspiratory effort developed more rapidly (-1.0+/-0.2 vs -0.6+/-0.1 cm H(2)O/s, p=0.019) and was more negative (-28.7+/-2.7 vs -20.3+/-1.6 cm H(2)O, p<0.001) on the breath preceding arousal.

CONCLUSIONS

Except for a heightened ventilatory drive response during airway occlusion, airway function and ventilatory compensation to ventilatory challenge appear to be similar, but with consistently and substantially delayed arousal responses, in SWS versus stage 2 sleep.