. Author manuscript; available in PMC: 2013 Jun 1.

Published in final edited form as: Plast Reconstr Surg. 2012 Jun;129(6):989e–998e. doi: 10.1097/PRS.0b013e31824ecd61

Table 6.

Statistical determination of pretest probability revision in 5 selected studies on diagnostic accuracy of sonography as a confirmatory test for carpal tunnel syndrome

	Pretest probability (prevalence)^†	Sensitivity	Specificity	Positive likelihood ratio	Negative likelihood ratio	Posttest probability^††
Kwon et al.²²	0.40	0.66	0.63	1.78	0.54	0.54	0.27
Pastare et al.²³	0.40	0.62	1.0	Inf^*	0.38	Inf^**	0.20
Altinok et al.²⁴	0.40	0.65	0.92	8.13	0.38	0.85	0.20
Kele et al.²⁵	0.40	0.74	0.98	37	0.26	0.96	0.15
El Mediany et al.²⁶	0.40	0.98	1.0	Inf^*	0.02	Inf^**	0.01

^†

We assumed a pretest probability of 0.40 because estimates from population studies suggest this is the approximate prevalence of CTS amongst patients that present to a primary care setting with the symptoms in the clinical scenario ²⁰

^††

The grayscale column represents posttest probability if the index test is positive and the clear column represents probability of absence of disease if the index test result is negative.

These studies reported specificities of 1. The positive likelihood ratio formula is; sensitivity/1−specificity, if the specificity is 1, the denominator is 0 which = infinity.

^**

Multiplication by infinity = infinity.