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Table 1 Loss to follow-up and missing data at two years of corrected age in a very preterm cohort

From: Strategies for assessing the impact of loss to follow-up on estimates of neurodevelopmental impairment in a very preterm cohort at 2 years of age

  Total surviving to 2 years olda Non-responders Responders
Total sample N = 1737 N = 796 (45.8%) N = 941 (54.2%)
Missing data Perinatal and SES variableab,c 251 (14.5%) 141 (17.7%) 110 (11.7%)
Neurodevelopmental impairment at 2 years CAb,d N/A N/A 104 (11.1%)
Portugal N = 603 N = 196 (32.5%) N = 407 (67.5%)
Missing data Perinatal and SES variablesa,d 72 (11.9%) 37 (18.9%) 35 (8.6%)
Neurodevelopmental impairment at 2 years CAb,d N/A N/A 19 (4.7%)
United Kingdom N = 1134 N = 600 (52.9%) N = 534 (47.1%)
Missing data Perinatal and SES variablesa,d 179 (15.8%) 104 (17.3%) 75 (14.0%)
Neurodevelopmental impairment at 2 years CAb,d N/A N/A 85 15.9%)
  1. aDeath excluded; Number of deaths before age 2: total:7, Portugal:2, United Kingdom:5 bSES socioeconomic status, CA corrected age csee text for data items dNeurodevelopmental assessment is a composite of motor disability and non-verbal cognitive disability