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Comment & Response
January 6, 2022

Use of Participation to Prevalence Ratio for Evaluating the Representation Status of Women in Oncology Clinical Trials

Author Affiliations
  • 1Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
JAMA Oncol. 2022;8(3):479-480. doi:10.1001/jamaoncol.2021.6968

To the Editor In their recent Research Letter in JAMA Oncology, Jenei et al1 reported that women with cancer had statistically significant lower enrollment rates than men in global cancer drug trials between 2000 and 2020. The results suggested that women were underrepresented in cancer clinical trials, which may undermine the generalizability of new cancer drugs in women. However, the authors only adopted the Pearson χ2 test to assess whether there is a significant difference between the enrollment of sexes. Our concern is that such direct comparison does not consider the different disease prevalence between men and women, which can contribute to the disproportionate participation evaluation by sex in clinical trials. Although the authors found that enrollment rates of women were not matched to their incidence (eg, thyroid and colon cancer), it is more appropriate to calculate the participation to prevalence ratio (PPR) by the following formula: percentage of women among trial participants/percentage of women among disease population, for evaluating the representation status of women in clinical trials.2 A PPR between 0.8 and 1.2 indicates that the proportion of women in clinical trials nearly equals the proportion of women in the disease population, and a PPR less than 0.8 or more than 1.2 indicates that women are either underrepresented or overrepresented, respectively. Notably, in a recent cross-sectional study investigating the representation status, Varma et al3 observed that women were adequately represented in premarketing (mean PPR, 0.91; 95% CI, 0.90-0.91) and postmarketing (mean PPR, 1.00; 95% CI, 1.00-1.01) studies of novel approved cancer drugs by calculating PPRs. The inconsistent results suggested in the conclusions of Jenei et al1 may be different after adjusting the participation rate by prevalence.

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