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. Author manuscript; available in PMC: 2016 Aug 4.
Published in final edited form as: Methods Inf Med. 2015 May 29;54(4):328–337. doi: 10.3414/ME14-01-0093

Table IV.

Linkage status by match variable, overall linkage

Linkeda
N = 2,188
Unlinkeda
N = 620
overall P test (if not Χ2)
Administrative variables
Demographics
 Age, years(median(IQR)) 6 (2–12) 4 (0–12) < 0.001 ranksum
 Admission year, mode(%) 2008 (31) 2010 (33) 0.01
 Discharge year, mode(%) 2008 (31) 2010 (35) 0.001
  Missing, n(%) 7 (1) 17 (1)
 Male, n(%) 1,373 (63) 397 (64) 0.54
  Missing, n(%) 1 (0) 1 (0)
 Insurance type, mode(%) “government”, (44) “government”, (49) 0.17
  Missing, n(%) 260 (12) 50 (8)
 Race/Ethnicity, mode(%) “white”, (54) “white”, (63) 0.003 exact
  Missing, n(%) 128 (6) 25 (4)
Hospital Course
 ICU admission, n(%) 2,090 (96) 585 (94) 0.23
 ICU days, median(IQR) 4 (2–10) 3 (2–8) < 0.001 ranksum
 Hospital LOS, days (median(IQR)) 8 (4–19) 6 (3–13) < 0.001 ranksum
  Missing, n(%) 1 (0) 5 (1)
 Discharge disposition, mode(%) “home”, (54) “home”, (50) < 0.001 exact
  Missing, n(%) 23 (1) 13 (2)
ICD-9-CM variables
Injury Severity
 Injury Mechanism, mode(%) “MVT”, (42) “MVT”, (36) 0.008
 Injury Severity Score (ISS) 17 (10–25) 17 (10–25) 0.009 ranksum
 Body region AIS scores
 Head, mode(%) 4 (37) 4 (42) 0.01 exact
 Number Non-Head AIS ≠ 0, median(IQR) 1 (0–3) 1 (0–2) < 0.001 ranksum
Proceduresb
 Total count, median(IQR) 1 (0–3) 1 (0–2) < 0.001 ranksum