Real-life effectiveness of omalizumab in severe allergic asthma above the recommended dosing range criteria.

BACKGROUND: Omalizumab (Xolair) dosing in severe allergic asthma is based on serum IgE and bodyweight. In Australia, patients eligible for omalizumab but exceeding recommended ranges for IgE (30-1500 IU/mL) and bodyweight (30-150 kg) may still receive a ceiling dose of 750 mg/4 weeks. About 62% of patients receiving government-subsidized omalizumab are enrolled in the Australian Xolair Registry (AXR). OBJECTIVES: To determine whether AXR participants above the recommended dosing ranges benefit from omalizumab and to compare their response to within-range participants. METHODS: Data were stratified according to dose range status (above-range or within-range). Further sub-analyses were conducted according to the reason for being above the dosing range (IgE only vs. IgE and weight). RESULTS: Data for 179 participants were analysed. About 55 (31%) were above recommended dosing criteria; other characteristics were similar to within-range participants. Above-range participants had higher baseline IgE [812 (IQR 632, 1747) IU/mL vs. 209 (IQR 134, 306) IU/mL] and received higher doses of omalizumab [750 (IQR 650, 750) mg] compared to within-range participants [450 (IQR, 300, 600) mg]. At 6 months, improvements in Juniper 5-item Asthma Control Questionnaire (ACQ-5, 3.61 down to 2.01 for above-range, 3.47 down to 1.93 for within-range, P < 0.0001 for both) and Asthma Quality of Life Questionnaire (AQLQ mean score (3.22 up to 4.41 for above-range, 3.71 up to 4.88 for within-range, P < 0.0001) were observed in both groups. Forced expiratory volume in one second (FEV1 ) improved among above-range participants. There was no difference in response between above-range and within-range participants. Above-range participants due to either IgE alone or IgE and weight had similar improvements in ACQ-5, AQLQ and FEV1 . CONCLUSIONS AND CLINICAL RELEVANCE: Patients with severe allergic asthma above recommended dosing criteria for omalizumab have significantly improved symptom control, quality of life and lung function to a similar degree to within-range participants, achieved without dose escalation above 750 mg.

Metrics of salbutamol use as predictors of future adverse outcomes in asthma.

BACKGROUND: Beta-agonist overuse is associated with adverse outcomes in asthma, however, the relationships between different metrics of salbutamol use and future risk are uncertain. OBJECTIVE: To investigate the relationship between metrics of salbutamol use and adverse outcome. METHODS: In a 24-week randomized controlled trial of 303 asthma patients at risk of severe exacerbations which compared the efficacy and safety of combination budesonide/formoterol inhaler according to a single inhaler regimen (SMART) with a fixed-dose regimen with salbutamol as reliever ('Standard'), actual medication use was measured by electronic monitoring (Australian New Zealand Clinical Trials Registry Number ACTRN12610000515099). A nested cohort study explored the relationship between metrics of baseline salbutamol use over 2 weeks and future severe asthma exacerbations, poor asthma control (ACQ-5 ≥ 1.5) or 'extreme' salbutamol overuse (> 32 salbutamol actuations/24-h period). RESULTS: Higher mean daily salbutamol use (per two actuations/day) [Odds ratio (OR) (95% CI) 1.24 (1.06-1.46)], higher days of salbutamol use (per 2 days in 2 weeks) [OR 1.15 (1.00-1.31)] and higher maximal 24-h use (per two actuations/day) [OR 1.09 (1.02-1.16)] were associated with future severe exacerbations. Higher mean daily salbutamol use was associated with future poor asthma control [OR 1.13 (1.02-1.26)]. Higher mean daily salbutamol use [OR 2.73 (1.84-4.07)], number of days of use [OR 1.46 (1.24-1.71)], and maximal daily use [OR 1.57 (1.31-1.89)] were associated with an increased risk of future extreme salbutamol overuse. CONCLUSION AND CLINICAL RELEVANCE: Electronically recorded frequency of current salbutamol use is a strong predictor of risk of future adverse outcomes in asthma, with average daily use performing the best. These findings provide new information for clinicians considering metrics of salbutamol as predictors of future adverse outcomes in asthma.

Identifying patient-specific beliefs and behaviours for conversations about adherence in asthma.

BACKGROUND: Asthma guidelines advise addressing adherence at every visit, but no simple tools exist to assist clinicians in identifying key adherence-related beliefs or behaviours for individual patients. AIMS: To identify potentially modifiable beliefs and behaviours that predict electronically recorded adherence with controller therapy. METHODS: Patients aged ≥ 14 years with doctor-diagnosed asthma who were prescribed inhaled corticosteroid/long-acting ß(2)-agonist (ICS/LABA) completed questionnaires on medication beliefs/behaviours, side-effects, Morisky adherence behaviour score and Asthma Control Test (ACT), and recorded spirometry. Adherence with ICS/LABA was measured electronically over 8 weeks. Predictors of adherence were identified by univariate and multivariate analyses. RESULTS: 99/100 patients completed the study (57 female; forced expiratory volume in 1 s mean ± standard deviation 83 ± 23% predicted; ACT 19.9 ± 3.8). Mean electronically recorded adherence (n= 85) was 75% ± 25, and mean self-reported adherence was 85% ± 26%. Factor analysis of questionnaire items significantly associated with poor adherence identified seven themes: perceived necessity, safety concerns, acceptance of asthma chronicity/medication effectiveness, advice from friends/family, motivation/routine, ease of use and satisfaction with asthma management. Morisky score was moderately associated with actual adherence (r=-0.45, P < 0.0001). In regression analysis, 10 items independently predicted adherence (adjusted R(2) = 0.67; P < 0.001). Opinions of friends/family about the patient's medication use were strongly associated with poor adherence. Global concerns about ICS/LABA therapy were more predictive of poor adherence than were specific side-effects; the one-third of patients who reported experiencing side-effects from their steroid inhaler had lower adherence than others (mean 62% vs 81%; P= 0.015). CONCLUSIONS: This study identified several specific beliefs and behaviours which clinicians could use for initiating patient-centred conversations about medication adherence in asthma.

Effect of different asthma treatments on risk of cold-related exacerbations.

Common colds often trigger asthma exacerbations. The present study compared cold-related severe exacerbations during budesonide/formoterol maintenance and reliever therapy, and different regimens of maintenance inhaled corticosteroids (ICS), with or without long-acting ß(2)-agonists (LABA), and with as-needed short-acting ß(2)-agonists (SABA) or LABA. Reported colds and severe exacerbations (defined by oral corticosteroid use and/or hospitalisation/emergency room visit) were assessed for 12,507 patients during 6-12 months of double-blind treatment. Exacerbations occurring ≤14 days after onset of reported colds were analysed by a Poisson model. The incidence of colds was similar across treatments. Asthma symptoms and reliever use increased during colds. Budesonide/formoterol maintenance and reliever therapy reduced severe cold-related exacerbations by 36% versus pooled comparators plus SABA (rate ratio (RR) 0.64; p=0.002), and for individual treatment comparisons, by 52% versus the same maintenance dose of ICS/LABA (RR 0.48; p<0.001); there were nonsignificant reductions versus higher maintenance doses of ICS or ICS/LABA (RR 0.83 and 0.72, respectively). As-needed LABA did not reduce cold-related exacerbations versus as-needed SABA (RR 0.96). Severe cold-related exacerbations were reduced by budesonide/formoterol maintenance and reliever therapy compared with ICS with or without LABA and with as-needed SABA. Subanalyses suggested the importance of the ICS component in reducing cold-related exacerbations. Future studies should document the cause of exacerbations, in order to allow identification of different treatment effects.

Measuring asthma control: a comparison of three classification systems.

There are various ways to classify asthma control; however, no classification is universally accepted. This retrospective analysis compared asthma control as assessed by the Asthma Control Questionnaire (5-item version; ACQ-5), Global Initiative for Asthma (GINA) or Gaining Optimal Asthma Control (GOAL) study criteria. Pooled data at the final study week (n = 8,188) from three budesonide/formoterol maintenance and reliever therapy studies which measured ACQ-5 were stratified according to GINA or GOAL criteria and ACQ-5 score distribution. The percentages of patients with a controlled/partly controlled week (GINA), totally/well-controlled week (GOAL) and range of ACQ-5 cut-off points were compared. Patients with GINA controlled, partly controlled and uncontrolled asthma had mean ACQ-5 scores of 0.43, 0.75 and 1.62, respectively. Patients with GOAL totally controlled, well-controlled and uncontrolled asthma had ACQ-5 scores of 0.39, 0.78 and 1.63. The kappa measure of agreement was 0.80 for GINA and GOAL criteria, and 0.63 for GINA controlled/partly controlled and ACQ-5 <1.00. ACQ-5 detected clinically important improvements in 49% of patients who, according to GINA criteria, remained uncontrolled at the end of the study. Asthma control measured by GINA or GOAL criteria provides similar results. GINA Controlled/Partly Controlled and GOAL Totally Controlled/Well-Controlled correspond to ACQ-5 <1.00. The ACQ-5 is more responsive to change in a clinical trial setting than a categorical scale.

Patient experiences of as-needed budesonide-formoterol by Turbuhaler® for treatment of mild asthma; a qualitative study.

BACKGROUND: Combination low-dose budesonide-formoterol, taken as-needed for symptom relief reduces exacerbation risk and is recommended for treatment of mild asthma. The NovelQ qualitative study explored patients' attitudes toward using this novel therapy. METHODS: Adults with mild asthma using reliever-only treatment were randomised to as-needed budesonide-formoterol Turbuhaler® in a multinational, 52-week open-label randomised controlled trial (NovelSTART-ACTRN12615000999538). A subgroup were interviewed to explore their attitudes to use of as-needed budesonide-formoterol after receiving it for ≥10 months. Semi-structured interviews were conducted until saturation, audio-recorded, and thematically analysed. RESULTS: Analysis of 35 participants (66% female; mean age 43.5 [range 18-74]; mean Asthma Control Questionnaire score 1.09 ± SD0.55) interviews identified 5 themes, each including both barriers and facilitators to therapy use. Themes were: 'Treatment effectiveness' i.e. how well symptoms were relieved and/or prevented; 'Lifestyle fit of the regimen' e.g. the extent to which the treatment regimen integrated into the patient's daily life; 'Attitudes toward medication use and safety' e.g. openness for new reliever treatments, beliefs about treatment necessity or side effects; 'Device attributes' e.g. perceived ease of use; and 'Doctor-patient relationship' e.g. impact of health professional support on new treatment acceptance. CONCLUSIONS: A wide range of factors seem to drive the opinions of mild asthma patients on as-needed budesonide-formoterol therapy. Many patients perceived both positive and negative treatment attributes, and their individual evaluation of these attributes determined their likelihood of using it after the study. Supportive patient-physician interactions appear key to addressing patient barriers. Recommendations for patient-centred discussions, developed from this research, are provided.

A new perspective on concepts of asthma severity and control.

Concepts of asthma severity and control are important in the evaluation of patients and their response to treatment but the terminology is not standardised and the terms are often used interchangeably. This review, arising from the work of an American Thoracic Society/European Respiratory Society Task Force, identifies the need for separate concepts of control and severity, describes their evolution in asthma guidelines and provides a framework for understanding the relationship between current concepts of asthma phenotype, severity and control. "Asthma control" refers to the extent to which the manifestations of asthma have been reduced or removed by treatment. Its assessment should incorporate the dual components of current clinical control (e.g. symptoms, reliever use and lung function) and future risk (e.g. exacerbations and lung function decline). The most clinically useful concept of asthma severity is based on the intensity of treatment required to achieve good asthma control, i.e. severity is assessed during treatment. Severe asthma is defined as the requirement for (not necessarily just prescription or use of) high-intensity treatment. Asthma severity may be influenced by the underlying disease activity and by the patient's phenotype, both of which may be further described using pathological and physiological markers. These markers can also act as surrogate measures for future risk.

Associations between inhaler technique and asthma control among asthma patients using pressurised MDIs and DPIs.

OBJECTIVES: To investigate associations between technique with pressurised metered-dose inhalers (pMDIs) and dry powder inhalers (DPIs) used as controller medication and asthma control variables measured using Asthma Control Test (ACT) scores. DESIGN: In this cross-sectional study, the inhaler technique of asthma patients using pMDIs or DPIs (Turbuhaler® [TH] and Accuhaler Diskus™ [ACC]) were assessed against published inhaler technique checklists. ACT scores (maximum 25, higher score corresponding to better asthma control) were assessed. RESULTS: Of the 130 subjects enrolled in the study (41 TH, 54 ACC and 35 pMDI), inhaler technique scores (out of nine for all devices) were low for TH (4.4 ± 0.9) and ACC (5.4 ± 1.0) compared with pMDI (8.1 ± 0.9) (P < 0.001, one-way analysis of variance). Older age and use of pMDI were associated with better inhaler technique. ACT scores were low, consistent with very poorly controlled asthma (mean TH 13.1 ± SD 3.9, mean ACC 13.3 ± SD 3.9 and mean pMDI 12.8 ± SD 4.2). No significant association between inhaler technique scores and ACT scores was found. More recent asthma diagnosis and a higher level of education were associated with higher ACT scores (better asthma control). CONCLUSION: Asthma control was poor in this population. Lack of a significant association between the inhaler technique score and asthma control may reflect the multiple factors contributing to poor asthma control in the Jordanian population.

Self-management support and other alternatives to reduce the burden of asthma and chronic obstructive pulmonary disease.

While pharmacotherapy is important in the management of asthma and chronic obstructive pulmonary disease, it is also important to consider additional interventions that can further reduce the burden of ill health for patients, their families and the health care system. In this review, the evidence in favour of self-management support that leads to successful self-care by the patient is reviewed, and the key components of successful strategies are outlined; areas where more research is needed are identified. In addition to self-management support, other methods of delivering care, such as telemonitoring, admission avoidance, assisted discharge schemes and use of lay educators, are reviewed.

Pharmacological strategies for self-management of asthma exacerbations.

Written action plans are effective within asthma self-management, but there are few guidelines about the specific medication adjustments which can be recommended for self-treatment of exacerbations. This review examines pharmacological strategies for self-management of asthma exacerbations in adults, including those for inhaled corticosteroid/long-acting beta2-agonist (ICS/LABA) users. Oral corticosteroids are well-established in clinical practice and clinical trials for the treatment of severe exacerbations, including during combination therapy. Evidence supports 7-10 days treatment, with no need to taper except to reduce side-effects. Doubling the dose of ICS is not effective. Several studies have shown benefit from high-dose ICS (2,400-4,000 microg beclomethasone equivalent) for 1-2 weeks. This may be achieved by adding a high-dose ICS inhaler to maintenance ICS or ICS/LABA therapy. There is inconclusive evidence about acutely increasing the dose of maintenance budesonide/formoterol for exacerbations, and no studies of this approach with fluticasone/salmeterol. For patients taking maintenance budesonide/formoterol, use of the same medication as-needed reduces exacerbations. Short-acting beta2-agonists are still effective in producing bronchodilation during combination therapy; however, a higher dose may be required. There is a need for further studies to clarify remaining issues about self-management of asthma exacerbations, particularly with regard to side-effects of treatment and patient acceptability.

Double blind randomised controlled trial of two different breathing techniques in the management of asthma.

BACKGROUND: Previous studies have shown that breathing techniques reduce short acting beta(2) agonist use and improve quality of life (QoL) in asthma. The primary aim of this double blind study was to compare the effects of breathing exercises focusing on shallow nasal breathing with those of non-specific upper body exercises on asthma symptoms, QoL, other measures of disease control, and inhaled corticosteroid (ICS) dose. This study also assessed the effect of peak flow monitoring on outcomes in patients using breathing techniques. METHODS: After a 2 week run in period, 57 subjects were randomised to one of two breathing techniques learned from instructional videos. During the following 30 weeks subjects practised their exercises twice daily and as needed for relief of symptoms. After week 16, two successive ICS downtitration steps were attempted. The primary outcome variables were QoL score and daily symptom score at week 12. RESULTS: Overall there were no clinically important differences between the groups in primary or secondary outcomes at weeks 12 or 28. The QoL score remained unchanged (0.7 at baseline v 0.5 at week 28, p = 0.11 both groups combined), as did lung function and airway responsiveness. However, across both groups, reliever use decreased by 86% (p<0.0001) and ICS dose was reduced by 50% (p<0.0001; p>0.10 between groups). Peak flow monitoring did not have a detrimental effect on asthma outcomes. CONCLUSION: Breathing techniques may be useful in the management of patients with mild asthma symptoms who use a reliever frequently, but there is no evidence to favour shallow nasal breathing over non-specific upper body exercises.

The need for standardisation of peak flow charts.

Peak expiratory flow (PEF) monitoring is recommended in asthma guidelines as a tool for assessing severity, monitoring response to treatment, detecting exacerbations, identifying triggers, and providing objective justification for treatment to the patient, but some clinicians have expressed concerns about its relevance in the management of asthma. We have identified a sevenfold variation in the scale of existing PEF charts, with resulting wide variation in the appearance of the same PEF date on different charts. There is an obvious need for standardisation of PEF charts to avoid confusion for patients and to allow development of pattern recognition skills by clinicians. Evidence is provided from visual perception studies to suggest that preference should be given to a horizontally compressed PEF chart to facilitate identification of exacerbations and of overall trends, but this needs to be formally evaluated by retrospective and prospective studies. It is hoped that clinical expertise in PEF pattern recognition can eventually be incorporated into electronic decision making algorithms, as has occurred in occupational asthma, but, in the meantime, the ideal PEF chart for asthma management will represent a compromise between ease of manual data entry and ease of interpretation.

Traditional and patient-centred outcomes with three classes of asthma medication.

Lung function is commonly used as the primary endpoint in asthma clinical trials, but it may not reflect changes which are important to patients. The present study compared changes in, and relationships between, traditional and patient-centred end-points during treatment with three classes of asthma medication. Subjects with mild-to-moderate asthma were randomised to double-blind, double-dummy crossover treatment with eformoterol 12 microg b.i.d. or montelukast 10 mg q.d., then single-blind treatment with fluticasone 250 microg b.i.d./placebo capsules, with 6-week treatment periods and 1-week washouts. Individual "traditional" end-points (symptoms, reliever use, forced expiratory volume in one second per cent predicted, morning peak expiratory flow, airway hyperresponsiveness) and "patient-centred" end-points (asthma control questionnaire, quality of life, patient global assessments) were assessed. Principal component analysis and linear modelling were used to explore overall rank orders for treatment, and relationships between outcomes. A total of 58 subjects were randomised. The rank order of benefit from eformoterol and fluticasone differed for three factors derived from principal component analysis (eformoterol>fluticasone for symptom/reliever use factor, fluticasone>eformoterol for lung function factor, eformoterol=fluticasone for patient-centred factor). Montelukast was ranked third for all three factors. A significant relationship between patient-based variables and lung function was found only for montelukast treatment. In asthma treatment, traditional end-points do not fully capture patient-centred benefits, and the relationship between end-points differs with medication class.

The reduction of rhinitis symptoms by nasal filters during natural exposure to ragweed and grass pollen.

BACKGROUND: Prototype nasal filters were developed to collect inhaled pollen. This study evaluated the efficacy of the filters for prevention of rhinitis symptoms during acute outdoor pollen exposure. METHODS: A randomized double-blind design was used. Subjects (n=46) with a history of autumn exacerbation of rhinitis and positive skin test to ragweed, Bermuda and/or Bahia grass wore either active or placebo nasal filters for 2 h in autumn in a park containing these species. Major and Total Symptoms scores were recorded at 0, 30, 60, 90 and 120 min. RESULTS: Subjects wearing active nasal filters had significantly reduced scores, at all time-points compared with placebo group (all P <0.05). Of 14 individual symptoms measured, seven were significantly reduced (number of sneezes, runny nose, itchy nose, sniffles, itchy throat; itchy eyes and watery eyes) and another three showed a trend towards lower severity. The nasal filters also enabled the resolution of existing symptoms. Maximal difference in symptoms was seen immediately after subjects had spent 20 min sitting beside a large patch of ragweed. CONCLUSION: This is the first clinical trial of a nasal filter. The results suggest it has potential for enhancing rhinitis management during acute allergen exposure.

When can personal best peak flow be determined for asthma action plans?

BACKGROUND: Written asthma action plans based on personal best peak expiratory flow (PEF) consistently improve health outcomes, whereas those based on predicted PEF do not. Guidelines state that personal best PEF should be assessed over 2-3 weeks during good asthma control, but it is unclear how long to wait after commencing or changing treatment. METHODS: Electronically recorded spirometric data from 61 subjects with initially poorly controlled asthma from a 72 week budesonide study were analysed. For each week, average morning pre-bronchodilator PEF was calculated and personal best PEF was determined as the highest PEF in the previous 2 weeks. The time to plateau was defined as the week beyond which no further improvement occurred. RESULTS: At baseline, average morning PEF was 61% predicted and personal best PEF was 87% predicted. Personal best PEF from twice daily monitoring increased to a plateau of 95% predicted (p<0.0001) after only 3 weeks of budesonide treatment. However, average morning PEF continued to improve for 3 months and "as needed" reliever use for 7 months. CONCLUSIONS: Personal best PEF is a useful concept for asthma self-management plans when determined as the highest PEF over the previous 2 weeks. With twice daily monitoring, personal best PEF reaches plateau levels after only a few weeks of corticosteroid treatment.

Which index of peak expiratory flow is most useful in the management of stable asthma?

Calculation of diurnal peak expiratory flow (PEF) variability using values before and after bronchodilator is no longer possible for many asthmatic patients because they now use beta-agonists "as needed" for symptoms rather than regularly. This study assesses the usefulness of a number of alternative PEF indices as markers of airway liability in subjects with stable, although not necessarily well-controlled, asthma. Forty-six adult subjects completed a questionnaire about symptoms and treatment in the previous 3 mo. Spirometric function and airway hyperresponsiveness (AHR) were assessed; AHR was expressed as dose response ratio (DRR) (maximal percent fall in FEV1 divided by final dose of histamine). Subjects recorded PEF morning and evening, before and after bronchodilator (if used) for 2 wk. Nine different PEF indices were calculated. Diurnal variability (amplitude percent maximum) without bronchodilator was significantly less than diurnal variability with bronchodilator. Normal indices of PEF lability were found in 42% of subjects with reduced maximal midexpiratory flow (MMEF). Most of the PEF indices correlated strongly with DRR, and less strongly with symptom score and airway obstruction. Minimum morning prebronchodilator PEF over a week (expressed as percent recent best or percent predicted) is recommended as the best PEF index of airway lability in patients with stable asthma because it correlates strongly with AHR, patients are more likely to comply with a once-daily reading, the calculation is simple, and regular use of a beta-agonist is not required.

Pitfalls in processing home electronic spirometric data in asthma.

Electronic spirometers offer the prospect of paperless home monitoring, but data quality is not automatically better than from conventional monitoring. The aim of this study was to determine the extent to which the quality and processing of self-recorded spirometric data from patients with asthma complied with international guidelines for spirometry. Data were from 33 subjects with poorly controlled asthma who had completed the first 9 weeks of a clinical budesonide trial. MicroMedical DiaryCard electronic spirometers were used to record three spirometric manoeuvres in twice-daily sessions. Confounding events were recorded in a paper diary. Within-session reproducibility was calculated for forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow (PEF) during the first week of run-in and week 9 of budesonide treatment. Geometric means of within-session reproducibility (mean difference between highest and second-highest value from each session over a one-week period) for FEV1, FVC and PEF were 76 mL, 116 mL and 18 L x min(-1), respectively, during run-in. Times of spirometric sessions varied widely, with some overlap between morning and evening session times. Manoeuvre-induced falls in PEF and FEV1 occurred only as often as expected by chance. Nonasthma events including equipment faults and painful conditions caused changes in spirometric results. Home spirometric monitoring can be carried out with excellent reproducibility in patients with asthma. However, quality-control issues are complex and an accompanying paper diary remains essential.

Standardization of ambulatory peak flow monitoring: the importance of recent beta2-agonist inhalation.

Standardization of conditions for peak expiratory flow (PEF) monitoring is much more difficult in practice than for laboratory spirometry. Patients are usually asked to record PEF before medication. The aim of this study was to determine the effect of prior bronchodilator use on PEF outcome measures in a clinical trial. Electronic PEF records from 43 subjects with poorly controlled asthma were examined to determine the frequency with which beta2-agonist was inhaled <4 h before PEF measurement, as such PEF are potentially "postbronchodilator". The effect of inclusion of such PEF values on improvement in PEF outcome measures after 8 weeks of inhaled budesonide was calculated. Subjects were asked to record PEF before medication. During run-in, the median frequency of postbronchodilator PEF was 29%, falling to 0% after 8 weeks of budesonide. Inclusion of postbronchodilator PEF led to an overestimation of average morning, evening and daily PEF during run-in (p<0.001). Improvement in these indices with treatment was, therefore, underestimated. Minimum morning PEF expressed as per cent personal best was unaffected. Subjects may not be able to withhold beta2-agonist for 4 h before every peak flow reading. This may change as the level of asthma control changes, leading to a systematic bias in clinical trial end-points or inaccuracy in individual treatment decisions. Simple changes to peak expiratory flow instructions and analysis are proposed.