Table 2

Descriptive statistics and odds ratios (ORs) from univariate multilevel models

Categories

Number of studies

Number of participants

Response rate (%)

Odds ratio


n

(%)

n

(%)

Med.

IQR*

OR

95%CI**

p†


Health professional

0.18


Doctor

236

(67)

219,859

(60)

59

44 to 72

1.00

-


Nurse

36

(10)

64,377

(18)

50

37 to 71

1.05

0.71 to 1.55


Allied

57

(16)

59,872

(16)

57

35 to 68

0.81

0.63 to 1.05


Mixed

21

(6)

21,382

(6)

62

45 to 74

0.77

0.57 to 1.05


Country

< 0.0001


US

130

(37)

179,589

(49)

51

38 to 65

1.00

-


Canada

34

(10)

36,976

(10)

53

38 to 67

1.13

0.82 to 1.55


Australia/New Zealand

20

(6)

14,736

(4)

53

38 to 68

1.13

0.76 to 1.68


UK/Ireland

82

(23)

51,790

(14)

62

52 to 76

1.69

1.34 to 2.14


Other European countries

48

(14)

59,235

(16)

63

59 to 73

1.72

1.30 to 2.28


Other countries

36

(10)

23,164

(6)

61

43 to 76

1.63

1.19 to 2.22


Length (minutes)

0.0005


<10

123

(35)

100,794

(28)

55

40 to 70

1.00

-


10-19

77

(22)

103,547

(28)

51

38 to 66

0.92

0.72 to 1.18


> = 20

42

(12)

62,465

(17)

52

40 to 67

0.94

0.70 to 1.27


No information

108

(31)

98,684

(27)

64

53 to 76

1.47

1.17 to 1.83


Number of reminders

0.08


0

176

(50)

176,886

(48)

53

38 to 70

1.00

-


1

79

(23)

75,253

(21)

60

49 to 68

1.25

0.99 to 1.57


2

47

(13)

41,995

(11)

61

51 to 74

1.28

0.97 to 1.70


3-5

37

(11)

56,207

(15)

62

50 to 72

1.35

0.99 to 1.83


No information

11

(3)

15,149

(4)

52

38 to 72

-

-


Number of survey participants

< 0.0001


> = 2,500

34

(10)

177,159

(48)

43

26 to 62

1.00

-


1000-2499

62

(18)

87,362

(24)

46

38 to 59

1.16

0.83 to 1.61


750-999

22

(6)

19,004

(5)

51

38 to 60

1.32

0.86 to 2.03


500-749

61

(17)

36,674

(10)

53

40 to 63

1.46

1.04 to 2.04


250-499

86

(25)

30,546

(8)

65

47 to 75

2.19

1.59 to 3.01


<250

85

(24)

14,745

(4)

66

58 to 75

2.66

1.93 to 3.66


Publication type

0.51


Electronic

75

(21)

75,409

(21)

60

44 to 71

1.00

-


Standard

275

(79)

290,081

(79)

58

44 to 71

0.93

0.74 to 1.16


All studies

350

(100)

365,490

(100)

59

42 to 71


* IQR = interquartile range

** 95%CI = 95% confidence interval

† p value from likelihood ratio test statistic comparing models with and without the listed categories of the specified factor

Odds ratios above 1.0 indicate a higher response rate in that category than in the reference group.

Cook et al. BMC Health Services Research 2009 9:160   doi:10.1186/1472-6963-9-160

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