Therapy and Management | Treatment | Daily practice | Ideal vs. real patient

Trial outcome and correct use of inhalation devices

In recent years treatment decisions have been directed away from the physician's clinical experience towards a more evidence-based approach. In order to avoid the influence of confounding factors the patient populations included in recently conducted controlled clinical trials have been highly selected. On the other hand it could be assumed that strictly selected patients will not represent the overall patient population and therefore extrapolation of treatment results may not be acceptable.

A large study including over 850 patients with obstructive lung diseases was conducted in order to find out, to which extent "real life" patients fitted into criteria commonly used in clinical research trials. Selection criteria for trials on asthma were absence of comorbidity, predicted FEV of 50-85%, 12% reversibility during last year, non-smoker. Less than 5.4% of the patients included in this study met with these criteria. Additional criteria as being symptomatic and regular use of inhaled corticosteroids reduced this number to 3.3%.

These results indicate that - even though large randomised trials providing high significances in favour of one treatment option over another exist - they may be of little use for treatment decisions in non-selected patients. Predictions concerning the outcome will be easier the more strict criteria are selected. Additionally a sufficient high number of patients will secure enough power to reach statistical significance.

Concerning the use of different devices several studies have also demonstrated that incorrect inhalation technique is common in patients with obstructive lung diseases. Since treatment efficacy is highly correlated with correct use of the inhalation device, this factor will certainly reduce treatment efficacy in "real world" patients compared with thoroughly instructed patients of controlled trials.

Literature:

Herland K, Akselen JP, Skjonsberg OH, Bjermer L. How representative are clinical study patients with asthma or COPD for a larger "real life" population of patients with obstructive lung disease? 2005. Respiratory Medicine; 99: 11-19

Hesselink AE, Penninx WJH, Wijnhoven HAH, Kriegsman DMW, vanEijk JTM. Determinants of an incorrect inhalation technique in patients with asthma or COPD. 2001. Scand J Prim Health Care; 19: 255-260

Lenney J, Innes JA, Crompton GK. Inappropriate inhaler use: assessment of use and patient preference of seven inhalation devices. 2000. Respiratory Medicine; 94: 496-500

Molimard M, Raherison C, Lignot S, Depont F, Abouelfath A, Moore N. Assessment of handling of inhaler devices in real life: an observational study in 3811 patients in primary care. 2003. Journal of Aerosol Medicine. 16 (3): 249-254

Mistakes according to the use of different kind of devices

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