Prediction formula for interrupter respiratory resistance in healthy Japanese adults

Interrupter respiratory resistance (Rint) measurement is useful for evaluating lung function in patients who cannot perform traditional pulmonary function tests. However, data on the prediction formulas for Rint in healthy Japanese adults are lacking. Our aims were to examine the relationship between Rint and sex, age, height, and weight, to establish prediction formulas, and to evaluate our new prediction formula (%Rint) in patients with asthma. Rint measurement was performed in 1,536 healthy adult subjects aged 21-80 years. This study was conducted according to ATS guidelines, which recommend obtaining 10 measurements to ensure a minimum of 5 technically acceptable interruptions (Am J Respir Crit Care Med 2007). Stepwise multiple linear regression analysis indicated that height was the most significant variable independently correlating with Rint. The Rint prediction formulas for our cohort based on height were: RintE = -0.03168 x height + 8.204084 and Rinti = -0.02985 x height + 7.920835. Both %RintE and %Rinti were significantly higher in patients with asthma than in normal subjects (%RintE; 135.2 +/- 26.4 vs. 98.6 +/- 25.5, %RintI; 142.4 +/- 30.4 vs. 98.6 +/- 27.4; p < 0.0001). We established prediction formulas of Rint for healthy Japanese adults. %Rint is useful in screening for asthma.