Prevalence and factors associated with suboptimal peak inspiratory flow rates in COPD

Sohini Ghosh1 Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, [email protected]

Roy A Pleasants2 Durham VA Medical Center, Durham, NC, USA

Jill A Ohar3 Department of Medicine, Section of Pulmonary, Critical Care, Allergy, and Immunology, School of Medicine, Wake Forest University, Winston-Salem, NC, USA

James F Donohue1 Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, [email protected]

M Bradley Drummond1 Division of Pulmonary Diseases and Critical Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA, [email protected]Correspondence[email protected]

Abstract

Purpose

Adequate peak inspiratory flow rate (PIFR) is required for drug dispersion with dry powder inhalers (DPIs). Prevalence of PIFR discordance (suboptimal PIFR with prescribed inhalers) and factors influencing device-specific PIFR are unclear in COPD. The objective of this study was to determine the prevalence of PIFR discordance and associated clinical factors in a stable COPD population.

Patients and methods

An observational, single-center, cohort study was conducted including 66 outpatients with COPD. PIFR was measured using the In-Check™ Dial with applied resistance of prescribed inhalers. Participants were defined as discordant if measured PIFR was <30 L/min and <60 L/min for high and low–medium resistance devices, respectively, using an inspiratory effort the participant normally used with their prescribed DPI.

Results

The median age of the COPD participants was 69.4 years, 92% were white and 47% were female. A total of 48% were using low–medium resistance DPIs (Diskus^®/Ellipta^®) and 76% used high-resistance DPI (Handihaler^®). A total of 40% of COPD participants were discordant to prescribed inhalers. Female gender was the only factor consistently associated with lower PIFR. Shorter height was associated with reduced PIFR for low–medium resistance (r=0.44; P=0.01), but not high resistance (r=0.20; P=0.16). There was no correlation between PIFR by In-Check™ dial and PIFR measured by standard spirometer.

Conclusion

PIFR is reduced in stable COPD patients, with female gender being the only factor consistently associated with reduced PIFR. Discordance with prescribed inhalers was seen in 40% of COPD patients, suggesting that many COPD patients do not generate adequate inspiratory force to overcome prescribed DPIs resistance in the course of normal use.

Keywords:

Supplementary materials

Figure S1 Distribution of peak inspiratory flow rate (PIFR) between female and male participants when measured against R2 low–medium resistance inhaler (eg, Diskus^® and Ellipta^®).

Figure S2 Distribution of peak inspiratory flow rate (PIFR) between female and male participants when measured against R5 high resistance inhaler (Handihaler^®).

Figure S3 Correlation between height (x-axis) and In-Check™ Dial (y-axis) with R2 low–medium resistance profile inhaler (eg, Diskus^® and Ellipta^®). Blue line represents fitted line with gray shading 95% CI of fitted line.

Figure S4 Correlation between height (x-axis) and In-Check™ Dial (y-axis) with R5 high resistance inhaler (Handihaler^®). Blue line represents fitted line with gray shading 95% CI of fitted line.

Figure S5 Correlation between peak inspiratory flow rate measured by standard spirometer (x-axis) and In-Check™ Dial (y-axis) with R2 low–medium resistance profile inhaler (eg, Diskus^® and Ellipta^®). Blue line represents fitted line with gray shading 95% CI of fitted line.

Figure S6 Correlation between peak inspiratory flow rate (PIFR) measured by standard spirometer (x-axis) and In-Check™ Dial (y-axis) with R5 high resistance profile inhaler (Handihaler^®). Blue line represents fitted line with gray shading 95% CI of fitted line.

Table S1 Repeatability of PIFR in COPD participants

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Acknowledgments

MBD was supported by R01HL125432-01A1 and SG was supported by T32HL007106-41. MBD had full access to all of the data in the study.

Author contributions

All authors contributed to data analysis, drafting and revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

RAP has research support from Boehringer-Ingelheim and GlaxoSmithKline, served on Advisory Board for GlaxoSmithKline and Teva, has served as speaker for AstraZeneca and Sunovion, and served on Data Safety Monitoring Board for Grifols. JAO has performed advisory consulting for Boehringer-Ingelheim, GlaxoSmithKline, Theravance, Novartis, and AstraZeneca. She also has an investigator-initiated research grant from Sunovion. JFD has served as advisor to AZ, GSK, Novartis, Mylan, Sunovion, and Theravance. MBD has performed advisory consulting for Boehringer-Ingelheim, GlaxoSmithKline, and AstraZeneca. There were no funders, thus no funders had a role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; and in the decision to publish the results. SG reports no conflicts of interest in this work.