It is simply not possible to detect all possible drug side effects in the drug-approval process because of small sample size, narrow study populations, and limited time course.
The mean proportion of criteria suggesting a narrower study population was 9% (5%to13%3%, range 0-50).
For each of the 52 trials the proportion of missing or modified criteria that would lead a reader to assume a broader or narrower study population was calculated.
Inversely, readers would assume a narrower study population if comorbidities were mentioned as exclusion criteria in the trial report but not in the protocol.
Most of the missing eligibility criteria (96%, 94% to 97%) and modified eligibility criteria (54%, 46%to62%2%) suggested broader study populations and most of the added eligibility criteria (86%, 74%to94%4%) suggested narrower study populations.
For each missing, modified, or added criterion, we considered whether the difference between protocol and publication would broaden or narrow the study population assumed by a reader of the publication.
In order to evaluate systematically the nationwide prevalence of IPF in different geographical areas, we narrowed the study population to five university hospital cities and their populations at the end of the year 2012.
Firstly, we narrowed the study population to individuals who had lived on the same floor for 5 years or longer prior to the census, thus excluding those who moved to the high rise more recently.
The expediency of combining groups of health workers to obtain an adequate or convenient sample size is outweighed by the benefits of more robust conclusions for a narrower and well defined study population.
The generalizability of our data is limited due to: (i) the study population having narrow inclusion criteria, (ii) patients being on PN only, and (iii) the low nitrogen-to-calorie ratio in the commercially available formulation that was used.
