Nocturnal temperature-controlled laminar airflow device for adults with severe allergic asthma: the LASER RCT.

BACKGROUND: Severe asthma exacerbations are costly to patients and the NHS, and occur frequently in severely allergic patients. OBJECTIVE: To ascertain whether or not nocturnal temperature-controlled laminar airflow (TLA) device usage over 12 months can reduce severe exacerbations and improve asthma control and quality of life compared with a placebo device, while being cost-effective and acceptable to adults with severe allergic asthma. DESIGN: A pragmatic, multicentre, randomised, double-blind, placebo-controlled, parallel-group, superiority trial with qualitative interviews. The trial included an internal pilot with qualitative focus groups. SETTING: Fourteen hospitals in the UK that manage patients with severe asthma. PARTICIPANTS: Adults (16-75 years) with severe, poorly controlled, exacerbation-prone asthma despite high-intensity treatment, and who are sensitised to a perennial indoor aeroallergen. INTERVENTION: Nocturnal, home-based TLA treatment using an Airsonett® (Airsonett AB, Ängelholm, Sweden) device. The comparator was a placebo device that was identical to the active device except that it did not deliver the laminar airflow. Participants were allocated 1 : 1 to TLA therapy or placebo, minimised by site, origin of case, baseline severe exacerbation frequency, maintenance oral corticosteroid use and pre-bronchodilator forced expiratory volume in 1 second. MAIN OUTCOME MEASURES: Primary outcome - frequency of severe asthma exacerbations occurring within the 12-month follow-up period, defined as worsening of asthma requiring systemic corticosteroids [≥ 30 mg of prednisolone or equivalent daily (or ≥ 50% increase in dose if on maintenance dose of ≥ 30 mg of prednisolone)] for ≥ 3 days. Secondary outcomes - changes in asthma control, lung function, asthma-specific and global quality of life for participants, adherence to the intervention, device acceptability, health-care resource use and cost-effectiveness. RESULTS: Between May 2014 and January 2016, 489 patients consented to participate in the trial, of whom 249 failed screening and 240 were randomised (n = 119 in the treatment group and n = 121 in the placebo group); all were analysed. In total, 202 participants (84%) reported use of the device for 9-12 months. Qualitative analyses showed high levels of acceptability. The mean [standard deviation (SD)] rate of severe exacerbations did not differ between groups [active 1.39 (1.57), placebo 1.48 (2.03); risk ratio 0.92, 95% CI 0.66 to 1.27; p = 0.616]. There were no significant differences in secondary outcomes for lung function, except for a reduction in mean daily peak expiratory flow [mean (SD) difference 14.7 l/minute (7.35 l/minute), 95% CI 0.32 to 29.1 l/minute; p = 0.045) for those in the active device group. There were no differences in asthma control or airway inflammation and no serious harms related to the device. No significant difference between the groups in quality-adjusted life-years gained over 1 year was observed. In addition, there was no difference in generic or disease-specific health-related quality of life overall, although statistically significant higher quality of life at month 6 was observed. Increases in quality of life were not sufficient to offset the annual costs associated with use of the TLA device. LIMITATIONS: Missing outcome data could have resulted in an underestimation of exacerbations and rendered the study inconclusive. CONCLUSIONS: Within the limits of the data, no consistent benefits of the active device were demonstrated, and the differences observed were not sufficient to make the device cost-effective. The types of patients who may benefit from the TLA device, and the reasons for large reductions in exacerbation frequency in severe asthma trials, which also incorporate other methods of recording exacerbations, need to be explored. TRIAL REGISTRATION: Current Controlled Trials ISRCTN46346208. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 29. See the NIHR Journals Library website for further project information.

Allergies (along with viruses) are common triggers of asthma exacerbations or 'attacks', which can cause suffering and frequent visits to the general practitioner or hospital. A new machine known as a temperature-controlled laminar airflow device, which remains at the bedside and is switched on every night, filters out allergy particles in the air of a patient's breathing zone, allowing their lungs to rest in clean air overnight. We tested whether or not this machine could improve the lives of those with severe allergic asthma. We recruited 240 people across 14 centres that treat severe asthma across the UK; approximately half received the active device and the other half received a machine that looked exactly the same but did not remove the allergens (a 'placebo' machine). One in five participants was recruited using newer methods of social media such as Facebook (Facebook, Inc., Menlo Park, CA, USA) and Twitter (Twitter, Inc., San Francisco, CA, USA). Participants found the machine easy to use and to live with and there were no significant side effects. The number of attacks reduced a lot in both participants using the active device and those who used the placebo device ­ two participants in five did not suffer any attacks during the trial. However, there was no difference in the number of attacks between the two groups. This might have been because participants did not record everything that happened to them. There was no difference in measurements showing how well the lungs were working, nor in participants' quality of life after 1 year of participating in the trial. Those who were interviewed told us that the study visits and questionnaires could be burdensome, although it was helpful to think more about their asthma. An improvement was seen in one aspect of participants' breathing as well as in their quality of life after 6 months of using the machine, but these potential health benefits could not outweigh the cost of the machine.

A functional comparison of ovine and porcine trypsins.

Trypsin was isolated from ovine and porcine pancreas using affinity chromatography on immobilized p-aminobenzamidine. Molecular masses of the two proteins were 23900 and 23435 Da, determined by matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometry. The purified trypsins were compared using the kinetic properties K(m) and k(cat) which were determined at pH 8.0 and between 25 and 55 degrees C. Comparison of the Michaelis constants for ovine and porcine trypsins toward N-alpha-benzoyl-arginine-p-nitroanilide (BapNA) indicated that ovine trypsin had higher affinity for this substrate than the porcine enzyme. The rates of the reactions catalysed by the two enzymes correlated strongly over the range of temperatures and substrate concentrations tested, as did the k(cat) values. The specific activity of ovine trypsin for BapNA was, on average, approximately 10% higher than that of the porcine enzyme over the range of conditions tested. Porcine trypsin was less susceptible to denaturation at low pH or high temperature than was ovine trypsin. Porcine and ovine trypsin produced seven identically sized fragments from auto-catalytic hydrolysis. Proposed regions of identity between ovine and porcine trypsins were I(54)-K(77), L(98)-R(107), S(134)-K(178) and N(209)-K(116). Hydrolysis of beta-lactoglobulin, egg white lysozyme or casein by ovine or porcine trypsin yielded virtually identical patterns of fragments although the rate at which fragments were produced, in the case of beta-lactoglobulin, differed between the two enzymes. On balance the two enzymes appear to be functionally identical in their action.