Predictors of Suboptimal Peak Inspiratory Flow Rate in COPD

Spirometer and stethoscope
Spirometer and stethoscope
Patients with COPD who have suboptimal peak inspiratory flow rate tend to have longer disease duration, be more symptomatic, have more severe airflow obstruction, and lower lung function, weight, and BMI.

NEW ORLEANS — Certain clinical characteristics may help identify patients with chronic obstructive pulmonary disease (COPD) at risk for suboptimal peak inspiratory flow rate (sPIFR), according to research presented at the CHEST Annual Meeting, held October 19 to 23, 2019, in New Orleans, Louisiana.

As the dry powder inhalers commonly prescribed for COPD do not benefit patients with sPIFR because they are unable to inhale the medication into their lungs, it is important to identify these patients. sPIFR has been observed in 19% to 78% of outpatients with stable COPD and 32% to 52% of inpatients before hospital discharge for COPD exacerbation treatment. Factors frequently associated with sPIFR are older age, female sex, lower forced vital capacity (FVC), shorter height, and inspiratory capacity percentage predicted.

Researchers pooled data from 2 randomized, controlled, phase 3 trials ( Identifier: NCT03095456 and Identifier: NCT02518139) to compare differences in baseline characteristics, forced expiratory volume in 1 second (FEV1), FVC, and PIFR between participants with sPIFR (n=273; 52%) and participants with optimal PIFR (oPIFR; n=252; 48%).

Among the 525 participants analyzed, 92% were white, 55% were taking inhaled corticosteroid plus long-acting beta agonist combination treatment, 46% were current smokers, and the mean age was 65 years (range, 43-87 years). The sPIFR participants were 59% men and 41% women, compared with the oPIFR participants, which were 66% men and 34% women. Compared with oPIFR participants, sPIFR participants had longer COPD duration (9.0 vs 10.8 years; P <.0001), had a longer smoking history (39.2 vs 41.3 years; P =.0003), and had significantly lower mean weight (86.7 vs 80.5 kg; P =.005) and body mass index (29.0 vs 27.8 kg2/cm; P <.0001).

sPIFR was associated with a lower mean percent predicted normal FEV1 (39.8 vs 54.7), baseline FVC (2.2 L vs 2.7 [0.7] L;), and baseline FEV1 (1.0 L vs 1.4 L; P <.0001 for all) vs oPIFR. Compared with oPIFR participants, sPIFR participants had more severe dyspnea even within the same category of airflow limitation (modified Medical Research Council grade >2; 70% vs 49%; P <.0001) and used more supplemental oxygen (22% vs 10%; P =.0001).

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The investigators concluded, “Our results suggest that clinical characteristics may be used to identify patients at risk for sPIFR who may not be able to derive adequate benefit from [dry powder inhalers]. In these patients, it may be beneficial to measure PIFR in addition to airflow limitation before considering treatment options for COPD.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Ohar J, Mahler D, Barnes C, Crater G. Predictors of suboptimal peak inspiratory flow rate in patients with COPD: analyses from the revefenacin phase-3 program. Presented at: CHEST Annual Meeting 2019; October 19-23, 2019; New Orleans, LA. Abstract 1171.