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Table 2 Missingness among the matching variables

From: Investigating increased admissions to neonatal intensive care in England between 1995 and 2006: data linkage study using Hospital Episode Statistics

Variable HES 1995 EPICure (1995) HES 2006 EPICure-2 (2006)
  Missing (%) Missing (%) Missing (%) Missing (%)
Date of birth 8807 (1.53) 0 (0.00) 4265 (0.68) 0 (0.00)
GA at birth 164006 (28.50) 0 (0.00) 336178 (53.23) 7 (0.25)
Sex 2616 (0.45) 0 (0.00) 3202 (0.51) 9 (0.33)
Discharge date 16912 (2.94) 373 (55.84)
Date of death 571417 (99.29) 268 (40.12)
Birth weight 152641 (26.52) 0 (0.00) 288014 (45.61) 26 (0.95)
Birth order 250718 (43.56) 0 (0.00) 224632 (35.57) 0 (0.00)
Delivery method 168018 (29.19) 1 (0.15)
Number.of babies 152378 (26.48) 0 (0.00) 209455 (33.17) 0 (0.00)
Previous pregnancies number 618692 (97.97) 101 (3.67)
Ethnic category 462999 (80.45) 0 (0.00)
Postcode 290462 (46.00) 1 (0.04)
Mother’s dob 273426 (43.30) 2750 (100.00)
Mother’s age at delivery 214999 (37.36) 4 (0.60) 273430 (43.30) 8 (0.29)
  1. Variables in each of the Hospital Episode Statistics and EPICure data sets that were used for matching in 1995 and 2006 and their levels of missingness. (HES (1995) n=575,509 (for the entire year); EPICure n=668 (March – December); EPICure 2 n=2,750; HES (2006) n=631,401)