. 2012 Dec 10;14(6):e175. doi: 10.2196/jmir.2105

Table 1.

Results for 200 equivalent topics across four evidence-based textbooks.

Variable	Best Practice	DynaMed	PIER	UpToDate
Number of topics with potential for updates	119	46	109	104
Proportion of 200 topics with potential for updates (95% CI)^a	60% (53%-66%)^b	23% (17%-29%)	55% (48%-61%) ^b	52% (45%-59%) ^b
Mean (CI) number of articles per topic in PLUS since last update^c	1.94 (1.46-2.42) ^b	0.48 (0.29-0.67)	1.56 (1.21-1.91) ^b	1.67 (1.25-2.09) ^b
Mean (CI) number of days since last update^c	435 (392-478) ^b	170 (131-209)	488 (423-554) ^b	427 (360-494) ^b

^a χ ² ₃=65.3, P<.001 comparing the four textbooks.

^bValues sharing a superscript ^b are not significantly different from one another at the P=.01 (Bonferroni correction).

^cOne-way ANOVA P<.001.