Real-life effect of long-acting β2-agonist withdrawal in patients with controlled step 3 asthma

Health and cost impact of stepping down asthma medication for UK patients, 2001-2017: A population-based observational study

BACKGROUND

Guidelines recommend stepping down asthma treatment to the minimum effective dose to achieve symptom control, prevent adverse side effects, and reduce costs. Limited data exist on asthma prescription patterns in a real-world setting. We aimed to evaluate the appropriateness of doses prescribed to a UK general asthma population and assess whether stepping down medication increased exacerbations or reliever use, as well as its impact on costs.

METHODS AND FINDINGS

We used nationwide UK primary care medical records, 2001-2017, to identify 508,459 adult asthma patients managed with preventer medication. Prescriptions of higher-level medication: medium/high-dose inhaled corticosteroids (ICSs) or ICSs + add-on medication (long-acting β2-agonist [LABA], leukotriene receptor antagonist [LTRA], theophylline, or long-acting muscarinic antagonist [LAMA]) steadily increased over time (2001 = 49.8%, 2017 = 68.3%). Of those prescribed their first preventer, one-third were prescribed a higher-level medication, of whom half had no reliever prescription or exacerbation in the year prior. Of patients first prescribed ICSs + 1 add-on, 70.4% remained on the same medication during a mean follow-up of 6.6 years. Of those prescribed medium/high-dose ICSs as their first preventer, 13.0% already had documented diabetes, cataracts, glaucoma, or osteopenia/osteoporosis. A cohort of 125,341 patients were drawn to assess the impact of stepping down medication: mean age 50.4 years, 39.4% males, 39,881 stepped down. Exposed patients were stepped down by dropping their LABAs or another add-on or by halving their ICS dose (halving their mean-daily dose or their inhaler dose). The primary and secondary outcomes were, respectively, exacerbations and an increase in reliever prescriptions. Multivariable regression was used to assess outcomes and determine the prognostic factors for initiating stepdown. There was no increased exacerbation risk for each possible medication stepdown (adjusted hazard ratio, 95% CI, p-value: ICS inhaler dose = 0.86, 0.77-0.93, p < 0.001; ICS mean daily = 0.80, 0.74-0.87, p < 0.001; LABA = 1.01, 0.92-1.11, p = 0.87, other add-on = 1.00, 0.91-1.09, p = 0.79) and no increase in reliever prescriptions (adjusted odds ratio, 95% CI, p-value: ICS inhaler dose = 0.99, 0.98-1.00, p = 0.59; ICS mean daily = 0.78, 0.76-0.79, p < 0.001; LABA = 0.83, 0.82-0.85, p < 0.001; other add-on = 0.86, 0.85-0.87, p < 0.001). Prognostic factors to initiate stepdown included medication burden, but not medication side effects. National Health Service (NHS) indicative prices were used for cost estimates. Stepping down medication, either LABAs or ICSs, could save annually around £17,000,000 or £8,600,000, respectively. Study limitations include the possibility that prescribed medication may not have been dispensed or adhered to and the reason for stepdown was not documented.

CONCLUSION

In this UK study, we observed that asthma patients were increasingly prescribed higher levels of treatment, often without clear clinical indication for such high doses. Stepping down medication did not adversely affect outcomes and was associated with substantial cost savings.

Pharmacogenetics of inhaled long-acting beta2-agonists in asthma: A systematic review

BACKGROUND

Long-acting beta2-agonists (LABA) are recommended in asthma therapy; however, not all asthma patients respond well to LABA. We performed a systematic review on genetic variants associated with LABA response in patients with asthma.

METHODS

Articles published until April 2017 were searched by two authors using PubMed and EMBASE. Pharmacogenetic studies in patients with asthma and LABA response as an outcome were included.

RESULTS

In total, 33 studies were included in this systematic review; eight focused on children (n = 6051). Nineteen studies were clinical trials, while 14 were observational studies. Studies used different outcomes to define LABA response, for example, lung function measurements (FEV₁ , PEF, MMEF, FVC), exacerbations, quality of life, and asthma symptoms. Most studies (n = 30) focused on the ADRB2 gene, encoding the beta2-adrenergic receptor. Thirty studies (n = 14 874) addressed ADRB2 rs1042713, 7 ADRB2 rs1042714 (n = 1629), and 3 ADRB2 rs1800888 (n = 1892). The association of ADRB2 rs1042713 and rs1800888 with LABA response heterogeneity was successfully replicated. Other variants were only studied in three studies but not replicated. One study focused on the ADCY9 gene. Five studies and a meta-analysis found an increased risk of exacerbations in pediatrics using LABA carrying one or two A alleles (OR 1.52 [1.17; 1.99]). These results were not confirmed in adults.

CONCLUSIONS

ADRB2 rs1042713 variant is most consistently associated with response to LABA in children but not adults. To assess the clinical value of ADRB2 rs1042713 in children with asthma using LABA, a randomized clinical trial with well-defined outcomes is needed.

Step-Down Therapy for Asthma Well Controlled on Inhaled Corticosteroid and Long-Acting Beta-Agonist: A Randomized Clinical Trial

BACKGROUND

Stepping down therapy when asthma is well controlled on combination inhaled corticosteroids (ICSs) and long-acting beta-agonists (LABAs) is recommended, but it is not known whether lowering the ICS dose or stopping LABA is superior.

OBJECTIVE

To evaluate whether step-down therapy with LABA is superior to one without; and, secondarily, to evaluate whether reducing the ICS dose while maintaining LABA is noninferior to remaining on stable-ICS/LABA.

METHODS

The study was a randomized, double-masked 3-arm parallel group trial in participants aged 12 years or older. Following an 8-week run-in, 459 participants were randomly assigned to continue medium-dose ICS/LABA, reduced-dose ICS/LABA, or ICS alone (LABA-step-off) and followed for 48 weeks. The primary outcome was time to treatment failure, a composite of health care utilization, systemic corticosteroid use, increase in rescue therapy, decline in lung function, or participant or physician decision.

RESULTS

Time to treatment failure did not differ significantly between reduced- ICS/LABA and LABA-step-off (hazard ratio, 1.07; 95.3% CI, 0.69-1.65, P = .76). Nor was there a difference between stable-ICS/LABA and reduced-ICS/LABA (hazard ratio, 1.11; 95% CI, 0.70-1.76; P = .67), but the 10% noninferiority margin was exceeded. Lung function declines and hospitalization rates were significantly greater in the LABA-step-off group.

CONCLUSIONS

The 2 step-down regimens did not differ in terms of treatment failure, although stopping LABA was associated with a decline in lung function and more hospitalizations. There was no evidence to support the noninferiority of reduced-ICS/LABA as compared with stable-ICS/LABA.