Macintyre and colleagues (MacIntyre et al., 2013) (Appendix 3) conducted another clinical trial that was also a cluster randomized clinical trial. For this trial, the investigators randomized 1669 health care workers at 68 Chinese emergency departments and respiratory wards by clusters into three groups: A group that wore surgical masks at all times, a second group wore N5 respirators while performing high-risk procedures and the third group wore N95 respirators at all times. Similar to the previous trial, they used the same primary end-points and operational definitions as the previous study: CRI, ILI and PCR- confirmed Influenza. The group added bacterial colonization as a fourth outcome.
The average number of participants in each cluster …show more content…
Randomization, clear primary end point and use of laboratory confirmed measurement all added validity to the study. There were some imbalances across the study arms that might have resulted in a confounding effect such as the difference in vaccination rates and risk exposures just like the 2011 trial, however, the investigators adjusted for these potential confounders using a multivariable Cox proportional hazards model which have helped minimize the threats to validity. In terms of generalizability, it is difficult to translate the results of this study to daily clinical practice. Although continuous use of N95 respirators was the most effective method of protection, they can be uncomfortable to wear and cannot be easily tolerated by all health care workers for long periods of time. Discomfort might lead to lack of compliance, as was demonstrated in the diary cards, thus increasing the risk for …show more content…
However, since this study was based on an experimental mechanical model, it does not represent the actual experience of a health care worker that has been exposed to an infectious agent. Factors such as ventilation, humidity, air flow and location of objects can affect virus dissemination, which can pose a confounding effect in a real situation. Additionally, the amount of viral copies shed by an actual patient and potentially inhaled by the health care worker, all of which can affect infectivity making it difficult to generalize the results to real clinical situations. Also, since the study only tested a specific surgical mask and N95 respirator models, the results cannot be generalized to other models that differ in material, fit and filtration capability. The highlight of this study was the effect of a tight seal or a good fit in the blocking Influenza particles, which have not been studied previously in surgical