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Table 2 Descriptive statistics and odds ratios (ORs) from univariate multilevel models

From: Response rates in postal surveys of healthcare professionals between 1996 and 2005: An observational study

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    
  1. * IQR = interquartile range
  2. ** 95%CI = 95% confidence interval
  3. † p value from likelihood ratio test statistic comparing models with and without the listed categories of the specified factor
  4. Odds ratios above 1.0 indicate a higher response rate in that category than in the reference group.