Perhaps, therefore, larger-scale ascertainment of more-homogeneous, more severely affected samples is the key to enhancing the chances of success in MDD.
However, there is no reason to suppose that this process would be differential by post code, and any incomplete ascertainment for more recent years of birth would be similar for all study locations.
Also, as most children will only be assessed in more detail if they 'fail' the ASQ, there may be some under ascertainment of this more moderate disability.
The current study identified all women with a history of preterm birth for analysis, thus providing a more complete ascertainment of exposure and more reliable estimate of the associations.
Quality of safety reporting was based on the following four criteria: (1) recruitment completeness among members of a clearly-defined cohort; (2) report of explicit definitions that allow for reproducible ascertainment of two or more harms; (3) assessment of patients status within seven days to one month of treatment; and (4) attrition rate ≤ 20% until first follow-up assessment [ 21, 23].
We could have reduced the likelihood for misclassification of the comorbidity measures by expanding the time-frame for ascertainment of comorbidity to more than one year, but a one-year time frame has been adopted in other studies [ 7- 9] and enables direct comparison with our results.
We therefore designed a prospective study with active surveillance to ensure good case ascertainment and the acquisition of more detailed clinical information.
However, even in patients with clinically acute disease, where overall levels of ascertainment are more standard, there are several issues that must be considered before valid comparisons of clinical outcome are made between treatment centres.
17 was included in all primary analyses, because it was more recent, included estimates for individual cancer types, and had more reliable ascertainment of cancer diagnoses through linkage with cancer registries and more comprehensive information on immunosuppressant use through a linkage to pharmacy claims.
Ascertainment of AEs was presented more objectively in RCTs compared to observational studies.
Smaller associations in that study could also have occurred if there was under-ascertainment of cases among children of more highly exposed mothers.
