Background

Spirometry is the gold standard test used for diagnosis of chronic obstructive diseases such as chronic obstructive pulmonary disease (COPD) and asthma. However, spirometry is associated with several drawbacks such as lack of availability, limited accessibility, high cost, challenges in performing the test, etc., that limits its use in routine clinical practice. Under-use of spirometry leads to under diagnosis of COPD and asthma. Cipla Limited has developed a new digital, portable, point-of-care spirometer Spirofy^TM, based on pneumotach flow-sensing technology, which can bridge the unmet need of availability and accessibility and is easy to use. Spirofy^TM has undergone laboratory validation and has proven to be a robust device and is also ATS compliant.

Objective

To compare the performance of two Spirofy^TM devices with that of Vitalograph Alpha Touch spirometer (used as a standard for comparison) in measuring the lung capacities of healthy subjects and those with asthma and COPD. This study also evaluated the inter-device variability between the two Spirofy^TM devices.

Methods

This is a randomized, open-label, three-way cross-over study
Cohort comprised healthy individuals, stable asthmatics and stable COPD patients aged >18 years with no history of disease exacerbations in the preceding 4 weeks
Each subject underwent 3 spirometry tests; one test each with the two Spirofy^TM devices and one with the Vitalograph Alpha Touch spirometer in a pre-determined randomized sequence generated for each of the devices

Results

The study recruited 102 subjects: 35 healthy individuals, 34 asthmatics and 33 COPD patients
The per-protocol population comprised 90 subjects (29 healthy individuals, 31 with asthma and 30 with COPD)

FEV₁ and FVC values measured by the devices demonstrated strong positive correlations with the Vitalograph spirometer for all the groups; overall, healthy subjects, asthmatics and COPD patients

Table 1. The comparative limits of agreement and correlation coefficients for FVC and FEV₁ in the per-protocol population

Parameter/Device	Statistics	Healthy	Asthma	COPD	Overall
FVC
1^TM vs Spirofy^TMVitalograph Alpha Touch	Correlation coefficient	0.906	0.963	0.905	0.963
	Mean difference	75.17	27.74	113	71.44
	95% limit of agreement	(-645.9, 796.2)	(-426.4, 481.9)	(-234.3, 460.3)	(-455, 597.9)
2^TM vs Spirofy^TMVitalograph Alpha Touch	Correlation coefficient	0.899	0.972	0.875	0.955
	Mean difference	72.76	-15.16	53	35.89
	95% limit of agreement	(-672, 817.5)	(-417.4, 387)	(-296, 402)	(-487.8, 559.6)
2^TM 1 vs Spirofy^TMSpirofy	Correlation coefficient	0.981	0.990	0.955	0.986
	Mean difference	-2.41	-42.90	-60.0	-35.6
	95% limit of agreement	(-272.9, 268.1)	(-289.9, 204.1)	(-321.6, 201.6)	(-295.5, 225.4)
₁FEV
1^TM vs Spirofy^TMVitalograph Alpha Touch	Correlation coefficient	0.931	0.974	0.964	0.981
	Mean difference	83.10	58.39	55.67	65.44
	95% limit of agreement	(-400.1, 506.3)	(-248.7, 365.4)	(-110.9, 222.3)	(-273.5, 404.4)
2^TM vs Spirofy^TMVitalograph Alpha Touch	Correlation coefficient	0.916	0.974	0.964	0.977
	Mean difference	72.76	31.61	37	46.67
	95% limit of agreement	(-559.6, 705.1)	(-275.7, 338.9)	(-147, 221)	(-365.6, 458.9)
2^TM 1 vs Spirofy^TMSpirofy	Correlation coefficient	0.982	0.991	0.981	0.991
	Mean difference	-10.34	-26.77	-18.67	-18.8
	95% limit of agreement	(-301, 280.4)	(-209.3, 155.7)	(-191.4, 154)	(-237.2, 199.6)

Figure 1. Dot plot for both the Spirofy^TM devices FEV₁/FVC ratio

For FEV₁/FVC ratio <0.7, sensitivity was 97.2%, specificity was 90.1% and accuracy was 93.3% for Spirofy^TM
The values of FVC and FEV₁ measured by Spirofy^TM1 & Spirofy^TM2 were within the predefined limits of agreement indicating a good agreement between both the devices

Conclusion

Spirofy^TM is a portable, easy-to-use device and is as accurate as the standard Vitalograph Alpha Touch spirometer for detecting airflow obstruction and can be used in clinical settings for the diagnosis of asthma and chronic obstructive pulmonary disease.

BMC Pulm Med. 2024 May 10:24(1):230. Doi: 10.1186/s12890-024-02972-4.