Table 2.

Association of baseline characteristics with average ocular discomfort in the past week on the Brief Ocular Discomfort Index, over time

	Baseline (N=535)			6 Months (N=481)			12 Months (N=488)
Characteristic	N	Mean(SD)	P-value*	N	Mean(SD)	P-value^a	N	Mean(SD)	P-value*
Gender
Male	101	39.6 (20.7)	0.06	90	35.4 (21.1)	0.96	88	31.0 (22.6)	0.42
Female	433	43.6 (18.7)		391	35.3 (21.4)		400	33.2 (22.3)
Ethnicity
Hispanic or Latino	68	41.5 (21.9)	0.53	51	34.7 (24.6)	0.82	55	33.5 (25.4)	0.81
Other	466	43.0 (18.7)		430	35.4 (20.9)		433	32.7 (21.9)
Race
White	397	42.9 (18.7)	0.93	363	34.6 (20.5)	0.34	370	32.6 (21.5)	0.86
Black	64	43.1 (22.1)		58	38.8 (25.2)		57	34.2 (24.4)
Other	73	42.1 (19.1)		60	36.5 (22.2)		61	32.1 (25.4)
Cigarette smoking
Never	366	42.2 (19.2)	0.93	329	33.7 (21.2)	0.34	337	31.3 (21.7)	0.86
Former	142	43.1 (18.5)		133	37.6 (20.4)		134	35.4 (23.1)
Current	26	49.6 (20.9)		19	47.9 (24.9)		17	41.8 (26.3)
Rheumatoid arthritis
No	485	42.7 (19.3)	0.75	439	35.3 (21.3)	0.79	446	32.6 (22.5)	0.55
Yes	49	43.7 (18.0)		42	36.2 (21.9)		42	34.8 (21.0)
Osteoarthritis
No	393	42.9 (19.3)	0.84	349	35.1 (22.0)	0.65	356	32.4 (22.7)	0.60
Yes	141	42.6 (18.6)		132	36.1 (19.5)		132	33.6 (21.3)
Diabetes
No	472	43.1 (18.8)	0.34	427	35.1 (21.1)	0.45	433	32.5 (22.2)	0.41
Yes	62	40.6 (21.8)		54	37.4 (22.8)		55	35.1 (23.2)
Depression
No	412	42.9 (19.4)	0.94	369	34.6 (21.6)	0.19	376	31.7 (22.7)	0.06
Yes	122	42.7 (18.1)		112	37.7 (20.4)		112	36.3 (20.9)
Taking anti-depressants
No	405	42.7 (19.4)	0.73	353	35.0 (21.9)	0.51	355	32.2 (22.6)	0.36
Yes	129	43.3 (18.4)		128	36.4 (19.7)		133	34.3 (21.8)
Fibromyalgia
No	522	42.9 (19.2)	0.72	469	35.3 (21.4)	0.72	477	32.7 (22.4)	0.69
Yes	12	40.8 (17.3)		12	37.5 (16.6)		11	35.5 (19.7)
Sjögren syndrome
No	455	42.4 (19.3)	0.29	408	34.9 (21.0)	0.51	416	32.1 (22.3)	0.37
Yes	52	45.4 (18.8)		47	37.0 (23.6)		46	35.2 (22.4)

T-test except that ANOVA was used for Race and Cigarette smoking