Chronic obstructive pulmonary disease and Occam’s razor
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* Brian C. Weiner

Thank you for bringing this interesting article to my attention.1

I am not certain why patients were excluded if they died during their stay in hospital. It seems that this would be an important outcome to assess.

The data seem to support that patients who had spirometry had more appropriate care. They had a higher likelihood of being prescribed drugs known to be effective for management of chronic obstructive pulmonary disease (COPD). After diagnosis by spirometry, prescribing of specific drugs apparently was guided empirically by the doctors who ordered the spirometry, and using drugs available in Ontario’s pharmacopeia. On a large scale, it looks like we are seeing a replay of the registration studies for these drugs, i.e., effective drugs versus placebo.

It would have been interesting to see results for all patients with COPD who were taking these drugs versus those with COPD who were not. Spirometry may have been excluded through the use of Occam’s razor.

## Footnotes

*   **Competing interests:** None declared.

## Reference

1.  Gershon A, Goldman G, Croxford R, et al. Outcomes of patients with chronic obstructive pulmonary disease diagnosed with or without pulmonary function testing. CMAJ 2017;189:E530–8.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTg5LzE0L0U1MzAiO3M6NDoiYXRvbSI7czoyMjoiL2NtYWovMTg5LzI4L0U5NDUuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9)