Assessing spirometry, exhaled nitric oxide, and asthma symptoms score as instruments for respiratory health evaluation among women in a low socioeconomic context: a cross-sectional study.

BACKGROUND

Asthma is a major public health burden worldwide and presents as a health service challenge in low-income countries with poor living conditions and limited access to healthcare services.

AIM: To assess the relationship between asthma symptom scores, doctor-diagnosed current asthma (DDCA), fractional exhaled nitric oxide (FeNO) levels, and spirometry measurements as methods for assessing the respiratory health of adult women in rural and urban households in Zimbabwe.

METHODS

Using a cross sectional study design, 790 adult women were recruited for the Household Air Pollution (HAP) and Lung Health study between March 2018 and December 2019 in Goromonzi and Harare communities in Zimbabwe. Using a validated interviewer-administered respiratory health questionnaire, we created the asthma symptom score with a cut-off point of ≥ 2 ([Formula: see text]implying none to modest symptoms and ≥ 2 suggesting moderate to severe symptoms) and DDCA categories based on responses to asthma related questions. Spirometry (n = 584) and FeNO (n = 258) measurements were performed, using standard validated techniques. Associations between spirometry z-scores, FeNO, asthma symptom score and the DDCA were analysed.

RESULTS

The 790 participants had an average age of 47.5 years (SD = 16.2). Asthma symptom score ≥ 2 was significantly associated with FeNO ≥ 50 ppb (p-value = 0.039) and the obstructive pattern (p-value = 0.018). Participants with DDCA had significantly increased FeNO (p-value < 0.001), a lower Forced expiratory volume in one second (FEV1) (p-value = 0.028) and significantly reduced ratio of FEV1/ forced vital capacity (FVC) z score values (p-value = 0.020). Abnormal FEV1 z score (p-value = 0.011), and obstructive pattern (p-value = 0.001) were also significantly associated with FeNO ≥ 50 ppb.

CONCLUSION

The results of our investigation indicated that those who with DDCA had significantly increased FeNO, and also DDCA was significantly associated with abnormal FEV1 z score, and obstructive pattern. Thus, using a structured and validated asthma symptoms questionnaire might potentially identify individuals with respiratory health symptoms that may require further respiratory health assessment at health facilities for comprehensive asthma diagnosis.