Blog Updates for September 2009

Sep 28, 2009. In PSA Screening and Early Detection - Part 5. More Diagnostic Testing Concepts we added another example:
A 2009 meta analysis of PSA testing [PMID: 1974436] summarized various studies on PSA accuracy with the following table:

	Study	Year	No	TP	FP	FN	TN	Sensitivity	Specificity
1	Aragona	2005	3171	1073	1695	98	305	0.92	0.15
2	Beneduce	2007	101	42	31	8	20	0.84	0.39
3	Ciatto	2004	410	167	171	18	54	0.90	0.24
4	Espana	1998	170	53	96	15	6	0.78	0.06
5	Fischer	2005	178	61	76	13	28	0.82	0.27
6	Hofer	2000	184	67	81	7	33	0.91	0.29
7	McArdle	2004	171	93	52	10	16	0.90	0.24
8	Ryden	2007	361	180	146	8	27	0.96	0.16
9	Unal	2000	59	30	10	0	19	1.00	0.66
10	Wymenga	2000	716	253	228	68	15	0.79	0.06

In terms of our previous 2x2 tables, for each study the TP (true positive) and FP (false positive) entries form the first row of the 2x2 table for that study and the FN (false negative) and TN (true negative) form the bottom row. In this notation Sensitivity = TP / (TP + FN) and Specificity = TN /(TN + FP) so that for example in the first row we have Sensitivity = TP / (TP + FN) = 1073 / (1073 + 98) = 0.92 and Specificity = TN /(TN + FP) = 305 / ( 305 + 1695 ) = 0.15 .

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Sep 5/09. In Prostate Cancer Calculators we added: This [site] describes how to carry out and calculate your fitness using the US Marines Fitness Test.