Reference no: EM133417654

Beta blockers are a class of drugs commonly used to treat hypertension. However, some studies have suggested that the use of beta blockers could also be of bene?t in patients with cancer, as these drugs could block the mechanisms that trigger cancer metastasis (i.e., the spread of a cancer cells from one site in the body to another). Given that metastasis is responsible for the vast majority of cancer-specific deaths, preventing metastasils could greatly improve cancer survival.

In a recent cohort study, investigators examined the association between use of beta blockers after ovarian cancer diagnosis and disease survival. In a large national healthcare system, they identi?ed persons diagnosed with ovarian cancer in 2014-2017. Using the comprehensive pharmacy database for the healthcare system, the investigators were able to identify and exclude patients who had a history of beta blocker use before their cancer diagnosis. This pharmacy database also allowed them to identify remaining patients who received a new prescription for a beta blocker at any time after their ovarian cancer diagnosis. Via medical records and administrative data, the investigators also had access to information regarding potential confounders and deaths that occurred in the cohort through the end of 2022.

1. In their primary analysis, the investigators compared ovarian cancer mortality rates among patients with ovarian cancer who did vs. did not receive beta blockers after their cancer diagnosis. For each comparison group, follow-up time was counted starting at the time of a patient's ovarian cancer diagnosis. After adjusting for confounding, the investigators observed a relative risk (R) of 0.72, indicating signi?cantly lower ovarian cancer mortality rates among those who had received beta blockers after their diagnosis. Although you believe that control for confounding was sufficient in this study, you also believe the association between post- diagnostic beta blocker use and ovarian cancer mortality is overestimated here (i.e., that the true RR is closer to I). What is the most likely reason for this overestimation of the association with beta blockers in this study? Explain your answer.

2. In addition to their analyses comparing ovarian cancer-speci?c mortality rates among those who did vs. did not receive beta blockers after their cancer diagnosis, the investigators conducted some analyses expanding or restricting their exposure de?nition. In one such analysis, they compared ovarian cancer-speci?c mortality rates among patients who did vs. did not receive a new prescription for any hypertension drug after diagnosis (including but not restricted to beta blockers). In contrast to the observed inverse association with beta blockers. the investigators observed no association with hypertension drug prescriptions overall. Assume that use of beta blockers after ovarian cancer diagnosis is truly associated with lower risk of ovarian cancer- specifrc mortality, as suggested by the investigators' primary analysis. How is it then possible that no association was observed with hypertension drug prescriptions overall?