Rural South Indian spirometry values show wide variation compared to existing prediction equations

Area of Science:

• Pulmonary medicine
• Public health
• Biostatistics

Background:

• India lacks standardized spirometry reference values due to its heterogeneity.
• Few recent studies exist, especially from South India.

Purpose of the Study:

• Develop reference equations for spirometry in rural South Indian adults.
• Compare these new equations with existing Indian spirometry equations.

Main Methods:

• Utilized data from 583 non-smoking, asymptomatic adults (≥30 years) from a 2018 Vellore survey.
• Developed equations for FEV1, FEV1/FVC, and FVC using 70% of data and validated with 30%.
• Compared predicted values with existing Indian equations.

Main Results:

• Vellore rural equations closely matched urban South Indian equations but improved FVC prediction in males and FEV1/FVC in females.
• Rural Vellore equations identified more males with airflow obstruction than urban equations.
• Significant variations were observed when compared to equations from other Indian regions.

Conclusions:

• Highlights the necessity for region-specific spirometry reference equations in India.
• Emphasizes the impact of social heterogeneity on lung function variability.
• Underscores the need for diverse rural and urban studies to define 'normal' lung function.