Table 3

Characteristics of linkage error for different patient groups

Matched patientsNon-matched patients
At least one false (n=115)All correct (n=25 671)p ValueTotal (n=25 786)At least one missed (n=1554)All correct (n=84 987)p ValueTotal (n=86 541)
Total(% of total)(% of total)
Age group
 <1 month14 (0.05)7749(ref)7763422 (0.49)13 215(ref)13 637
 1–12 months48 (0.19)80608108509 (0.59)23 26823 777
 1–4 years39 (0.15)44874526315 (0.36)20 84921 164
 5–10 years12 (0.05)26112623177 (0.20)12 14912 326
 11+ years2 (0.01)27640.52*2766126 (0.15)15 405<0.001*15 531
 Missing0005 (0.01)1010.03106
Sex
 Male81 (0.31)14 711(ref)14 792862 (1%)47 567(ref)48 429
 Female34 (0.13)10 9600.0110 994674 (0.78%)37 2810.9637 955
 Missing00018 (0.02%)139<0.001157
Ethnic group
 White34 (0.13)15 150(ref)15 184562 (0.65)52 590(ref)53 152
 Mixed2 (0.01)5760.5557825 (0.03)18040.931829
 Asian10 (0.04)23400.07235089 (0.10)63940.676483
 Black11 (0.04)1021<0.001103269 (0.08)32190.0013288
 Other8 (0.03)579<0.001587114 (0.13)1905<0.0012019
 Missing50 (0.19)6005<0.0016055695 (0.08)19 075<0.00119 770
Admission
 Planned42 (0.16)10 01210 054673 (0.78)32 439(ref)33 112
 Unplanned73 (0.28)15 6590.5915 732881 (1.02)52 548<0.00153 429
Deprivation
 Low32 (0.12)7083(ref)7115270 (0.31)20 314(ref)20 584
 Middle38 (0.15)68616899311 (0.36)21 19421 505
 High25 (0.10)67860.48*6811254 (0.29)22 2000.09*22 454
 Missing†20 (0.08)49410.624961719 (0.83)21 279<0.00121 998
Provider size
 Small47 (0.18)8900(ref)8947535 (0.62)31 102(ref)31 637
 Medium24 (0.09)72757299606 (0.70)27 02627 632
 Large44 (0.17)94960.53*9540413 (0.48)26 8590.18*27 272
  • *p Values for linear trend across groups (univariate).

  • †Typically due to missing postcode data.