Correlation between handgrip strength and air trapping in patients with stable chronic obstructive pulmonary disease

Abstract

Background: Chronic obstructive pulmonary disease (COPD) often presents with dyspnea resulting from the condition of air trapping, assessed by lung volume measurement studies. This study aimed to investigate the relationship between handgrip strength (HGS) and air trapping in COPD patients.

Methods: Cross-sectional research was conducted in COPD patients at Thammasat University Hospital, Thailand between May 2022 and December 2023. HGS was assessed using the Jamar^® Smart Hand Dynamometer, and air trapping was measured using a body plethysmograph. Air trapping was defined as a ratio of residual volume (RV) to total lung capacity (TLC) greater than 40%. Receiver operator characteristic (ROC) curves, sensitivity, and specificity values were calculated to determine the optimal cutoff value of HGS for predicting air trapping.

Results: A total of 72 patients (90.3% male) were included, with an average age of 72.4±9.7 years. The body mass index was 23.5±4.3 kg/m². The smoking history was 23.2±14.8 pack-years. Common comorbidities included hypertension (36.1%) and diabetes (22.2%). Post-bronchodilator forced expiratory volume in 1 second (FEV1) was 72.1%±21.2%. Air trapping was found in 55.6%. A negative correlation was found between HGS and RV/TLC (R=-0.399, P=0.001). The best cutoff value for HGS to predict air trapping was 28.3 kg, with 71.9% sensitivity and 65.0% specificity. The area under the ROC curve for identifying air trapping was 0.681 (95% CI: 0.554 to 0.808, P=0.009).

Conclusions: Air trapping is common in COPD patients, and HGS is significantly correlated with air trapping. Thus, HGS may serve as an alternative tool for assessing air trapping.

Keywords: Chronic obstructive pulmonary disease (COPD); air trapping; handgrip strength (HGS); sensitivity; specificity.

Figure 1

Flowchart of COPD patient recruitment to the study. BD, bronchodilator; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; HGS, hand grip strength.

Figure 2

The correlation between RV/TLC and HGS. The equation for predicting air trapping, predicted RV/TLC (%) =59.63 − 0.51 × HGS. HGS, hand grip strength; RV, residual volume; TLC, total lung capacity.

Figure 3

The ROC plot of HGS and predicting air trapping. The best cutoff value of HGS for predicting air trapping is 28.3 kg, with 71.9% sensitivity and 65.0% specificity. The area under the ROC curve for identifying air trapping was 0.681 (95% CI: 0.554 to 0.808, P=0.009). HGS, hand grip strength; ROC, receiver operating characteristic; CI, confidence interval.