Table 1.

Hazard Ratios From Cox Regression With Year As the Only Predictor

	Estimated Hazard Ratio	95% Confidence Interval	P Value
yr1	0.80	0.66, 0.98	.027
yr2
97–98 vs 95–96	0.67	0.35, 1.26	.21
99–00 vs 95–96	0.47	0.21, 1.04	.064
yr3
98–00 vs 95–97	0.59	0.32, 1.10	.098

Note: yr1, year treated as a continuous variable; yr2, categorizing year into 3 groups 1995–1996, 1997–1998, and 1999–2000; yr3, categorizing year into 2 groups 1995–1997 and 1998–2000.