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Outcome of very preterm birth: children reviewed with ease at 2 years differ from those followed up with difficulty
Insights
Population prevalence studies risk bias by excluding hard-to-reach individuals. Those with severe disabilities or who are difficult to trace are often missed, underestimating true prevalence rates.
Area of Science:
- Neonatal care
- Epidemiology
- Disability studies
Background:
- Population prevalence studies aim to capture health status across a population.
- Accurate ascertainment of all individuals is crucial for reliable prevalence data.
Purpose of the Study:
- To investigate if individuals easily assessed in a population prevalence study differ from those with follow-up difficulties.
- To identify potential biases in prevalence studies due to participant accessibility.
Main Methods:
- A cohort of babies born before 32 weeks gestation in Northern England (1983, 1990, 1991) was traced.
- Surviving infants were assessed at two years by independent clinicians.
Main Results:
- The study identified higher rates of severe disability in infants who were difficult to trace (e.g., in care, missed appointments) compared to easily assessed infants.
- Excluding hard-to-trace survivors would have underestimated the true disability rate by nearly half (6.9% vs. 11.0%).
Conclusions:
- Population prevalence studies that do not account for individuals reluctant to cooperate risk significant ascertainment bias.
- Efforts to improve follow-up and engagement are essential for accurate health surveillance.
Aim:
To determine whether those most easily reviewed in a population prevalence study differ from those followed up only with difficulty.
Methods:
All babies born before 32 weeks of gestation in the North of England in 1983, 1990, and 1991 were traced, and all the survivors assessed at two years by one of two independent clinicians.
Results:
818 of the 1138 live born babies survived to discharge. There was some non-significant, excess disability in the 5% of long term survivors who were difficult to trace because of social mobility, but eight times as much severe disability in the 1% (9/796) in care and in the 5% (38/796) whose parents initially failed to keep a series of home or hospital appointments for interview, and five times as much emergent disability in the 2.7% (22/818) who died after discharge but before their second birthday. Had the babies who were seen without difficulty been considered representative of all the babies surviving to discharge, the reported disability rate would have been two thirds what it really was (6.9% instead of 11.0%).
Conclusions:
Population prevalence studies that ignore those who seem reluctant to cooperate risk serious ascertainment bias.
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