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Table 5 Relationship between provision of data required to calculate NNS and RCT characteristics

From: The external validity of published randomized controlled trials in primary care

Characteristics Data required to calculate NNS provided in report, n(%) Odds Ratio (95% CI) P Value
  NO YES   
  (n = 45) (n = 103)   
Journal     0.37
BMJ 14 (31) 44 (43) -  
British Journal of General Practice 15 (33) 31 (30) 0.66 (0.28 to 1.56)  
Family Practice 7 (16) 17 (16) 0.77 (0.27 to 2.24)  
Journal of Family Practice 9 (20) 11 (11) 0.39 (0.13 to 1.13)  
Number of enrolees     0.09
<100 8 (18) 40 (39) -  
110–260 20 (44) 31 (30) 0.31 (0.12 to 0.80)  
260–650 9 (20) 15 (15) 0.33 (0.11 to 1.02)  
>650 8 (18) 17 (16) 0.42 (0.14 to 1.32)  
Multicentre     0.45
Multiple 33 (73) 83 (81) -  
Single 11 (24) 16 (16) 0.58 (0.24 to 1.38)  
Unclear 1 (2) 3 (3) 1.19 (0.12 to 11.88)  
Funding Source     
Charity 5 (11) 10 (10) -  
Governing body 2 (4) 3 (3) 0.75 (0.09 to 6.04)  
Government 11 (24) 55 (53) 2.5 (0.71 to 8.76)  
Pharmaceutical Industry 7 (16) 8 (8) 0.57 (0.13 to 2.50)  
Other 5 (11) 9 (9) 0.9 (0.19 to 4.17)  
Not Listed 15 (33) 18 (17) 0.6 (0.17 to 2.14)  
Intervention Studied     0.02
Counselling/Lifestyle 3 (7) 8 (8) -  
Decision Support aids 1 (2) 6 (6) 2.25 (0.18 to 27.37)  
Educational 5(11) 21 (21) 1.56 (0.30 to 8.17)  
Pharmaceutical therapy 14 (32) 9 (9) 0.24 (0.05 to 1.16)  
Surgery/procedure 0 (0) 3 (3) undefined  
Other 21 (48) 55 (54) 0.98 (0.24 to 4.06)