Reference spirometric values in healthy Nicaraguan male workers.

The main objective was to derive reference equations for the FVC, FEV1, and FEV1/FVC ratio for healthy Nicaraguan male workers without current occupational exposure to agents hazardous to the lungs. Age, height, and weight were included as independent variables in the analysis, but only age and height showed significant effects on the indices studied. A nonlinear relationship with age was observed for FVC and FEV1, with a shift in the slope at the age of 32 years. Linear, quadratic, and multiphase models were tested in order to assess the best reference equation. The multi-phase model most closely fitted the values measured. The FEV1/FVC ratio showed a significant linear negative correlation with age. A comparison between the equations derived from this material and those reported in other studies revealed substantial differences. Racial, genetic, nutritional, work and sociocultural factors could account for the differences.