Table 3.

Relation Between Caffeine Intake and Parkinson Disease According to Hormone Use^* Among Postmenopausal Women, National Institutes of Health-AARP Diet and Health Study, 1995–2006

Quintile of Caffeine Intake	Never Users of Hormones				Ever Users of Hormones
	No. With PD	No. Without PD	ORa	95% CI	No. With PD	No. Without PD	ORa	95% CI
1	28	11,903	1.00	Referent	48	15,302	1.00	Referent
2	27	9,724	1.24	0.73, 2.10	38	13,000	0.93	0.60, 1.43
3	31	12,177	1.10	0.65, 1.84	30	14,902	0.66	0.42, 1.05
4	21	9,405	1.00	0.56, 1.77	23	12,420	0.64	0.39, 1.05
5	17	8,949	0.95	0.51, 1.77	13	9,365	0.53	0.28, 0.98
P for trend			0.57				0.02

Abbreviations: CI, confidence interval; OR, odds ratio; PD, Parkinson disease.

^*P for interaction = 0.16.

^aAdjusted for age at baseline, race, duration of smoking, and physical activity.