Table 4 Variation in odds ratios (95% CIs) and percentage bias for demographic risk factors for hospital readmission within one year according to HESID, comparing data linkage algorithms
Reference standard (n = 175,773)Deterministic (n = 181,395)Det+Probabilistic (n = 176,990)
Odds ratio (95% CI)Odds ratio (95% CI)BiasaOdds ratio (95% CI)Biasa
1-year readmission raten18.7%n18.4%n18.7%
Total175,773181,395176,990
Maleb85,8871.08 (1.05, 1.10)88,2431.07 (1.04, 1.10)6%90,3031.07(1.05, 1.10)2%
Femaleb89,710(reference)92,818(reference)86,484(reference)
Age group
0 to 3119,7423.39 (3.22, 3.58)123,7122.88 (2.74, 3.02)13%120,1863.40 (3.23, 3.58)0%
4 to 714,856(reference)15,510(reference)15,137(reference)
8 to 1110,7871.08 (1.00, 1.16)11,3060.99 (0.92, 1.06)119%10,9451.07 (0.99, 1.15)15%
12 to 158,9200.94 (0.87, 1.02)9,1860.83 (0.77, 0.89)9,0490.93 (0.86, 1.00)
16 to 1910,0801.19 (1.11, 1.28)10,2391.04 (0.97, 1.12)77%10,2431.18 (1.10, 1.27)6%
20 to 2311,3881.31 (1.23, 1.41)11,4421.15 (1.07, 1.23)50%11,4301.31 (1.23, 1.41)1%
Ethnic group
Missing44,7330.52 (0.50, 0.54)47,5180.51 (0.50, 0.54)−1%45,0440.52 (0.51, 0.54)1%
White103,831(reference)106,070(reference)104,603(reference)
Mixed3,9780.96 (0.88, 1.05)4,0050.98 (0.90, 1.07)3,9890.97 (0.88, 1.05)
Asian11,4810.98 (0.93, 1.04)11,7310.98 (0.93, 1.04)11,5430.99 (0.94, 1.04)
Black6,4570.78 (0.73, 0.84)6,5570.81 (0.75, 0.87)13%6,4910.80 (0.75, 0.86)9%
Chinese/Other5,2930.73 (0.67, 0.79)5,5140.72 (0.67, 0.78)−3%5,3200.73 (0.68, 0.79)3%
Socio-economic group
Missing50,3220.04 (0.03, 0.04)51,7460.03 (0.02, 0.04)−1%50,5460.04 (0.03, 0.04)0%
Not deprived89,966(reference)92,727(reference)90,631(reference)
Deprived34,5631.17 (1.14, 1.21)35,7491.16 (1.12, 1.19)9%34,8841.17 (1.13, 1.20)2%
No fixed abode7820.58 (0.46, 0.74)1,0310.40 (0.28, 0.56)−70%7870.60 (0.47, 0.77)7%
Foreign1400.42 (0.20, 0.86)1420.42 (0.20, 0.87)2%1420.47 (0.23, 0.95)14%
Data year
1998 to 200349,456(reference)53,463(reference)49,895(reference)
2004 to 200950,3481.83 (1.77, 1.91)51,4291.92 (1.85, 1.99)−7%50,7511.82 (1.76, 1.89)1%
2010 to 201575,9692.08 (2.01, 2.16)76,5032.20 (2.12, 2.28)−7%76,3442.08 (2.00, 2.16)0%
  • a This refers to the percentage by which the log odds coefficient in each model is over-or under-estimated, compared to the reference standard model 100*[(logitreference−logitcomparison/logitreference)], shown where the subgroup has a significantly increased risk of readmission in one year

  • b Models exclude records were sex is missing (n = 334 after deterministic match, 203 after probabilistic match and 176 for reference standard)