Predictors of incorrect inhalation technique in patients with asthma or COPD: a study using a validated videotaped scoring method.

BACKGROUND Inadequate technique reduces the effects of inhalation medication. Errors in inhalation technique have been reported to range up to 85%. Not only various patients' characteristics but also the device has an effect on correct inhalation technique. The purpose of this study was to determine the effect of patients' characteristics and type of inhaler device on inhalation technique in patient with asthma or chronic obstructive pulmonary disease (COPD). METHODS A validated scoring method was used that consisted of triple viewing of video-recorded inhalations, using device-specific checklists. The following patient characteristics were investigated: gender, age, education level, diagnosis, treatment by a pulmonary physician, previously received inhalation instruction, exacerbation frequency, knowledge, self-management competence, pulmonary function, and use of multiple inhaler devices. Chi-square statistics were used for univariate associations between potential determinants and correctness of inhalation technique. Relevant determinants were entered into a multivariate logistic regression model. Moreover, inhalation technique errors were examined for six inhaler devices: three prefilled dry powder inhalers, one single-dose dry powder inhaler, a pressurized metered-dose inhaler (pMDI) and a pMDI with a spacer. RESULTS Overall, 40% of the patients made at least one essential mistake in their inhalation technique. Patients who never received inhalation instruction and patients who used more than one inhaler device made significantly more errors (odds ratio both 2.2). Comparison between devices showed that a correct inhalation technique most likely occurred with the use of prefilled dry powder devices. CONCLUSION Incorrect inhalation technique is common among asthma and COPD patients in a pulmonary outpatient clinic. Our study suggests that the use of prefilled dry powder inhalers as well as inhalation instruction increases correct inhalation technique. Simultaneous use of different types of inhalation devices has to be discouraged.