Development of a Japanese version of the Modified Questionnaire on the Pulmonary Functional Status and Dyspnea

A Japanese version of the Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M) was made through a translation-backtranslation procedure under agreement with the original author, Dr. Lareau, SC. Three components of the Japanese version, dyspnea with activities (DA), fatigue with activities (FA), and change experienced by patients with activities (CA), were tested using 63 chronic respiratory disease (CRD) patients. Cronbach's alpha was the same, 0.93, for DA, FA and CA. Average values for DA, FA, and CA were significantly associated with the MRC and BDI scores in 63 patients. In 43 Chronic Obstructive Pulmonary Disease (COPD) patients, average values for DA, FA, and CA were significantly associated with the % predicted FEV1.0. After 26 patients were randomly selected, the same protocol was repeated with a 10- to 14-day interval to validate the reproducibility of the PFSDQ-M. Correlation coefficients were 0.94, 0.88, and 0.91 for DA, FA, and CA, respectively. Then, 52 patients were randomly selected and the same protocol was repeated with a 6- to 12-month interval to evaluate the sensitivity of PFQD-M. The changes in DA, FA and CA with the 6- to 12-month interval were significantly associated with changes in MRC and TDI. In 37 COPD patients, changes in DA, FA, and CA with the 6- to 12-month interval were significantly associated with the changes in the % predicted FEV1.0. These results show that the Japanese version of PFSDQ-M is valid in its reproducibility and internal consistency, and may also have construct validity and sensitivity for evaluating the functional status and dyspnea of patients with chronic respiratory illness.