Is the completion time of a questionnaire a pivotal factor when proving feasibility?

TO THE EDITOR: With great interest, I read Dr. Nonaka's,1 "Comparative study of 2 different questionnaires in Japanese patients: the quality of life and utility evaluation survey technology questionnaire (QUEST) versus the frequency scale for the symptoms of gastroesophageal reflux disease questionnaire (FSSG)." I totally agree the miscomprehensions due to the difficulty of the questions are important reasons why several questionnaires have not been widely used in clinical settings. Furthermore, the complexity of questionnaires could be more problematic to old patients as a result of the age-related declines in cognitive functions.2 Considering Korea's rapidly aging population, easier questionnaire would be more useful in clinical setting if no difference exists in the sensitivity, specificity and accuracy between questionnaires.

Prior to the use in clinical trials, questionnaires need to be tested for validation of three characteristics: reliability, validity and responsiveness.3,4 Reliability is defined by the extent to which a questionnaire produces the same results for each repeated trial. Validity refers to whether the questionnaire meets its expected function or role in a trial. Finally, responsiveness describes whether the questionnaire is capable of detecting changes in a condition over time, which might reflect therapeutic effects.5 Another important characteristic of any measurement procedure is feasibility. When evaluating the feasibility of a questionnaire, questionnaires regarding the patients' preferences were evaluated by calculating the satisfaction rate,6 or the number of times each patient consulted aid from the assessing investigators.7

The study by Nonaka et al1 lucidly indicated that the completion time of a questionnaire is a pivotal factor when proving feasibility, revealing that the FSSG questionnaire was easier for the Japanese patients to complete than that from QUEST. In fact, it is important to make a questionnaire brief and easy for patients. However, time-efficiency is just one of the important factors in the feasibility study. Other factors such as the patients' satisfaction and response rate should be taken into account as well. And also, shorter completion time on the FSSG could be caused by asking different type of questions, instead of complexity of questions. Other limitations of the study by Nonaka et al1 may include a relatively small sample size and wide age distribution of enrolled subjects. A group of older people may require more completion time than it would take with younger group. Nevertheless, the study by Nonaka et al1 has a strong point that it is the first to evaluate feasibility by calculating completion time of the questionnaire.