The phrase "actively ascertained" is correct and usable in written English.
It can be used when discussing the process of determining or finding out information in a deliberate and engaged manner.
Example: "The researchers actively ascertained the participants' opinions through detailed surveys and interviews."
Alternatives: "diligently determined" or "proactively discovered".
Deaths among non-respondents were actively ascertained.
Deaths within WIHS are actively ascertained.
They were actively ascertained through pathology departments across seven of nine French hospitals in which prostate cancer is diagnosed in the Montréal metropolitan area.
Cases were all patients newly diagnosed with primary histologically confirmed PCa, actively ascertained through pathology departments across seven French hospitals in the Montreal area between 2005 and 2009.
The UK registries updated the life status of patients included in this study by linking death certificates to the registry records; all other registries actively ascertained the life status of cases from various sources of information (e.g. registry of general practitioners, municipality files).
MACDP actively ascertains infants and fetuses with birth defects born to mothers residing in one of five metropolitan Atlanta counties at delivery (Clayton, Cobb, DeKalb, Fulton, and Gwinnett).
Other pulse oximetry screening studies that did actively ascertain patients that died at home from missed heart disease reported prevalences of duct dependent heart disease in the screened population virtually identical to ours, at 1.3/1000 and 1.2/1000.
21 They claimed a sensitivity of 77%, but this is optimistic as they did not actively ascertain patients dying in the community with undiagnosed heart disease, and the reported incidence of critical heart disease (35/50 008) is surprisingly low at only 0.7/1000 compared with the 1.3/1000 in our study.
Adults with aphasia were actively recruited to ensure that their views were ascertained [ 29].
3) Gastrointestinal symptoms attributed to study medication were ascertained during the DPP and for those participants actively taking metformin during the DPPOS.
We found information on diagnosis in hospital records, which we actively searched for deceased subjects (vital status and cause of death were ascertained for all the cohort members through 1999); incident cancer cases (ascertained through the regional cancer registry for all the cohort members from 1987 to 1999); and all other claimant workers.
