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. Author manuscript; available in PMC: 2014 Sep 2.
Published in final edited form as: Arch Pediatr Adolesc Med. 2009 Mar;163(3):203–210. doi: 10.1001/archpediatrics.2008.563

Table 2.

Characteristics of Cases vs Matched Controls Aged 1 to 4 Years

No. (%)b
Characteristica Cases
(n=61)
Controls
(n=134)
P Valuec
Demographic
 Age, y, mean (SD) 2.62 (1.01) 2.71 (1.03) .77
 Sexd .78
  F    25 (41)    56 (42)
  M    36 (59)    78 (58)
 Race .04
  White    35 (57)    84 (72)
  Nonwhite    26 (43)    32 (28)
 Household income, $ .03
  >50000    25 (48)    83 (70)
  ≤50000    27 (52)    36 (30)
 Education of respondente .003
  >High school    25 (44)    84 (73)
  ≤High school    32 (56)    31 (27)
 Children <6yin household .16
  No    24 (42)    63 (55)
  Yes    33 (58)    52 (46)
Environmental
 Exposure to water, May-Sep, time/mo .15
  ≤1    22 (37)    37 (28)
  >1    38 (63)    97 (72)
 Exposure to water, Oct-Apr, time/mo .12
   ≤1    46 (87)    98 (80)
  >1      7 (13)    24 (20)
 Of those with a pool .68
  Four-sided fence    10 (33)    27 (44)
  Property fence      7 (23)    12 (19)
  No fence    13 (43)    23 (37)
Health and development
 Able to climb ladder .30
  No    18 (30)    43 (38)
  Yes    42 (70)    70 (62)
 Able to open sliding door .41
  No    26 (50)    66 (59)
  Yes    26 (50)    45 (41)
 Able to walk well .30
  No      0      5 (4)
  Yes    61 (100)  113 (96)
 Risk taking score, mean (SD) 2.07 (0.48) 1.90 (0.46) .03
 Temperament score, mean (SD) 2.74 (0.38) 2.84 (0.32) .06
 General health .11
  Excellent/very good/good    57 (93)  114 (98)
  Fair/poor      4 (7)      2 (2)
 Seizure disorder .79
  No    60 (98)  130 (98)
  Yes      1 (2)      3 (2)
 Other medical condition .07
  No    49 (80)  120 (91)
  Yes    12 (20)    12 (9)
Swimming lessons
 Formal .002
  No    59 (97)    99 (74)
  Yes      2 (3)    35 (26)
 Informal instructionf .24
  Never/rarely/sometimes    25 (42)    42 (35)
  Every or most of the time    35 (58)    78 (65)
Comfort in water
 Liked the water .65
  No    14 (23)    27 (20)
  Yes    47 (77)  106 (80)
 Comfortable in water .71
  Uncomfortable/slightly uncomfortable    12 (20)    18 (15)
  Comfortable/very comfort    49 (80)  101 (85)
 Comfortable putting whole head in water .36
   No    38 (64)    70 (59)
   Yes    21 (36)    49 (41)
Swimming ability
 Float on back for 10 s .01
  No    57 (95)  110 (82)
  Yes      3 (5)    24 (18)
 Swim on stomach 15 ft .07
  No    59 (97)  120 (90)
  Yes      2 (3)    14 (10)
 Jump in a pool/swim 5 ft/back to wall .07
  No    59 (97)  106 (88)
  Yes      2 (3)    14 (12)
a

Characteristic of case or control, except where specified in headings.

b

Totals vary slightly because of missing data; percentage of distribution based on a denominator of those with information.

c

P value from the Wald statistic of a conditional logistic regression model containing only that variable.

d

Although cases and controls were matched by sex, we were not able to find sex-matched controls for all cases.

e

Asked only if the respondent lived with the child.

f

Assessed by asking how often the child received informal instructions, pointers, or tips about swimming or water safety when he or she went swimming.