Table 4. Estimated RRs of surgical modalities compared with previous year by Poisson's analysis.

	RR	Wald 95% confidence limits		P-value
TURP
40s	1.0472	0.9392	1.1675	0.4062
50s	1.0319	0.9998	1.065	0.0515
60s	0.9962	0.9812	1.0114	0.6237
70s	1.0867	1.069	1.1046	<0.0001
80s	1.0753	1.0412	1.1105	<0.0001
Open prostatectomy
Whole agea	0.9448	0.9001	0.9916	0.0215
Hyperthermia
40s	0.9439	0.9124	0.9765	0.0009
50s	0.9448	0.922	0.9681	<0.0001
60s	0.9119	0.8913	0.933	<0.0001
70s	0.864	0.8353	0.8936	<0.0001
80s	0.6813	0.6241	0.7439	<0.0001
Laser
40s	1.0486	0.9315	1.1805	0.4317
50s	1.5337	1.477	1.5927	<0.0001
60s	1.0049	0.9736	1.0372	0.7612
70s	1.0296	0.9891	1.0718	0.1542
80s	0.9713	0.8781	1.0744	0.5719

Abbreviation: RRs, relative risks.

^aIn open prostatectomy group, interaction between age and study year was not significant (P=0.5863), so estimated RR is considered as whole age.