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Table 2 Responders at 3 months

From: The effect of postal questionnaire burden on response rate and answer patterns following admission to intensive care: a randomised controlled trial

  Group A (n = 2466) Group B (n = 2315) p All (n = 4781)
Age median, [IQR] 65 [53–74] 65 [53–74] 0.99c 65 [53–74]
Male sex (%) 57% 57% 0.87b 57%
APACHE II score median, [IQR] 15 [11–19] 14 [11–19] 0.08a 15 [11–19]
ICU length of stay days median [IQR] 3 [2–6] 3 [2–6] 0.33a 3 [2–6]
Hospital length of stay days median [IQR] 15 [9–26] 15 [8–25] 0.23a 15 [8–25]
Reason for ICU admission n (%)     
Respiratory tract infection 237 (10) 192 (8) 0.16b 429 (9)
Major vascular procedure 185 (8) 171 (7) 0.93b 356 (7)
Large bowel tumour 148 (6) 173 (7) 0.07b 321 (7)
Acute renal failure 109 (4) 90 (4) 0.42b 199 (4)
Chronic obstructive pulmonary disease 79 (3) 76 (3) 0.95b 155 (3)
Bowel perforation 66 (3) 47 (2) 0.18b 113 (2)
Septicaemia/septic shock 60 (2) 61 (3) 0.73b 121 (3)
Oesophageal neoplasm 56 (2) 70 (3) 0.14b 126 (3)
Status epilepticus 52 (2) 44 (2) 0.69b 96 (2)
Self-poisoning 44 (2) 53 (2) 0.27b 97 (2)
Not recorded 77 (3) 64 (3) 0.53b 141 (3)
Other 1353 (55) 1274 (55)   2627 (55)
Self-reported demographics n (%)     
Current address Usual address 2305 (93) 2165 (94)   4470 (93)
  Family 36 (1) 38 (2)   74 (2)
  Rehabilitation 19 (1) 11 (0)   30 (1)
  Other 36 (1) 38 (2)   74 (2)
  Not usual (unspecified) 13 (1) 10 (0)   23 (0)
  Missing 57 (2) 53 (2) 0.79b 110 (2)
Higher education Yes 985 (40) 983 (42)   1968 (41)
  No 1235 (50) 1138 (49)   2373 (50)
  Missing 246 (10) 194 (8) 0.07b 440 (9)
University degree Yes 580 (24) 600 (26)   1180 (25)
  No 1700 (69) 1579 (68)   3279 (69)
  Missing 186 (8) 136 (6) 0.02b 322 (7)
Current employment status Full time 245 (10) 213 (9)   458 (10)
  Part time 108 (4) 129 (6)   237 (5)
  Seeking 27 (1) 35 (2)   62 (1)
  Retired 1353 (55) 1250 (54)   2603 (54)
  Sick 380 (15) 376 (16)   756 (16)
  Housework 120 (5) 110 (5)   230 (5)
  Student 24 (1) 17 (1)   41 (1)
  Other 112 (5) 97 (4)   209 (4)
  Missing 97 (4) 88 (4) 0.47b 185 (4)
Prior employment status Full time 437 (18) 388 (17)   825 (17)
  Part time 189 (8) 190 (8)   379 (8)
  Seeking 38 (2) 24 (1)   62 (1)
  Retired 1233 (50) 1170 (51)   2403 (50)
  Sick 168 (7) 169 (7)   337 (7)
  Housework 132 (5) 105 (5)   237 (5)
  Student 27 (1) 16 (1)   43 (1)
  Other 75 (3) 87 (4)   162 (3)
  Missing 167 (7) 166 (7) 0.28b 333 (7)
Carer now Yes 150 (6) 152 (7)   302 (6)
  No 2207 (89) 2052 (89)   4259 (89)
  Missing 109 (4) 111 (5) 0.64b 220 (5)
Carer prior Yes 159 (6) 170 (7)   329 (7)
  No 1844 (75) 1680 (73)   3524 (74)
  Missing 463 (19) 465 (20) 0.2b 928 (19)
Assistance Answered 246 (10) 288 (12)   534 (11)
  Unable 68 (3) 42 (2)   110 (2)
  Unspecified 21 (1) 26 (1)   47 (1)
  No 2050 (83) 1893 (82)   3943 (82)
  Missing 81 (3) 66 (3) 0.01b 147 (3)
Mental problems now Yes 334 (14) 298 (13)   632 (13)
  No 2034 (82) 1912 (83)   3946 (83)
  Missing 98 (4) 105 (5) 0.52b 203 (4)
Mental problems prior Yes 354 (14) 331 (14)   685 (14)
  No 1730 (70) 1636 (71)   3366 (70)
  Missing 382 (15) 348 (15) 0.9b 730 (15)
  1. n (%), median [interquartile range]
  2. p values not corrected for multiple testing
  3. aMann-Whitney U test (non-parametric)
  4. bChi-squared test
  5. cWelch’s t-test
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BMC Medical Research Methodology

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