Table 2.

Baseline (Pre-Index) Patient Characteristics by Cohort

	Development Cohort		Validation Cohort		P Valuea	Total Cohort
	n	%	n	%		n	%
Demographics
Number	48,840		24,416			73,256
Age, years
65-69	9,259	19.0	4,694	19.2	0.1925	13,953	19.0
70-74	12,500	25.6	6,378	26.1		18,878	25.8
75-79	11,796	24.2	5,722	23.4		17,518	23.9
80-84	9,752	20.0	4,885	20.0		14,637	20.0
85-89	5,533	11.3	2,737	11.2		8,270	11.3
Mean (SD)	76.0 (6.3)		75.9 (6.3)		0.1864	76.0 (6.3)
Median [range]	76 [65-89]		75 [65-89]			76 [65-89]
Gender
Male	20,887	42.8	10,282	42.1	0.0913	31,169	42.5
Female	27,953	57.2	14,134	57.9		42,087	57.5
Race/ethnicity
Caucasian	34,290	70.2	17,045	69.8	0.1796	51,335	70.1
African American	11,118	22.8	5,668	23.2		16,786	22.9
Hispanic	1,956	4.0	1,014	4.2		2,970	4.1
Other/unknown	1,476	3.0	689	2.8		2,165	3.0
Geographic region
Northeast	783	1.6	396	1.6	0.9970	1,179	1.6
Midwest	9,705	19.9	4,848	19.9		14,553	19.9
South	34,611	70.9	17,296	70.8		51,907	70.9
West	3,741	7.7	1,876	7.7		5,617	7.7
Plan type
HMO	26,317	53.9	12,992	53.2	0.1621	39,309	53.7
PPO	13,837	28.3	6,966	28.5		20,803	28.4
Other	8,686	17.8	4,458	18.3		13,144	17.9
Low-income subsidy	7,753	15.9	3,971	16.3	0.1751	11,724	16.0
Medical Characteristics
Comorbidities
Chronic conditions
Hypertension	35,346	72.4	17,761	72.7	0.2875	53,107	72.5
Hyperlipidemia	33,086	67.7	16,604	68.0	0.4760	49,690	67.8
Diabetes	17,235	35.3	8,752	35.8	0.1377	25,987	35.5
Congestive heart failure	3,342	6.8	1,642	6.7	0.5511	4,984	6.8
Physical/mental disabilities
Joint disorders	7,489	15.3	3,796	15.5	0.4506	11,285	15.4
Muscle weakness/neuropathy/movement disorders	5,472	11.2	2,773	11.4	0.5358	8,245	11.3
Mental disorders	4,826	9.9	2,547	10.4	0.0196	7,373	10.1
Glaucoma-related measures
Glaucoma diagnosis	40,347	82.6	20,237	82.9	0.3560	60,584	82.7
Open-angle glaucoma diagnosis (by an ophthalmologist)	26,965	55.2	13,659	55.9	0.0603	40,624	55.5
Glaucoma-related eye exam	24,975	51.1	12,526	51.3	0.6717	37,501	51.2
Glaucoma surgery	1,612	3.3	807	3.3	0.9736	2,419	3.3
Other
Number of physicians seen, mean (SD)	8.6 (6.5)		8.8 (6.5)		0.0080	8.7 (6.5)
Median [range]	7 [0-84]		8 [0-72]			8 [0-84]
Medical costs per member, mean (SD)	$5,332 ($11,062)		$5,470 ($11,315)		0.0043	$5,378 ($11,147)
Median [range]	$1,988 [$0-$310,074]		$2,061 [$0-$382,728]			$2,013 [$0-$382,728]
Pharmacy Characteristics
New (vs. continuing) user	14,930	30.6	7,439	30.5	0.7786	22,369	30.5
Mail order (index script)	16,950	34.7	8,518	34.9	0.6262	25,468	34.8
Pharmacy Characteristics
Source of index prescription
Written	23,747	48.6	11,898	48.7	0.6175	35,645	48.7
Electronic	11,807	24.2	5,789	23.7		17,596	24.0
Phone	5,012	10.3	2,516	10.3		7,528	10.3
Fax	7,912	16.2	4,012	16.4		11,924	16.3
Other	362	0.7	201	0.8		563	0.8
Formulary tier (index prescription)
Tier 1	6,581	13.5	3,297	13.5	0.9860	9,878	13.5
Tier 2	34,222	70.1	17,120	70.1		51,342	70.1
Other	8,037	16.5	3,999	16.4		12,036	16.4
Prescriber specialty (index prescription)
Ophthalmologist	31,291	64.1	15,621	64.0	0.9834	46,912	64.0
Optometrist	8,238	16.9	4,133	16.9		12,371	16.9
Family practitioner/internal medicine	2,059	4.2	1,020	4.2		3,079	4.2
Other/unknown	7,252	14.8	3,642	14.9		10,894	14.9
Prescriber gender (index prescription)
Male	31,947	65.4	15,944	65.3	0.4559	47,891	65.4
Female	7,096	14.5	3,491	14.3		10,587	14.5
Unknown	9,797	20.1	4,981	20.4		14,778	20.2
Rx-Risk-V score, mean (SD)	6.0 (2.9)		6.0 (2.9)		0.0718	6.0 (2.9)
Median [range]	6 [1-20]		6 [1-20]			6 [1-20]
Number of pharmacies visited, mean (SD)	2.1 (1.1)		2.1 (1.1)		0.5577	2.1 (1.1)
Median [range]	2 [1-25]		2 [1-12]			2 [1-25]
Pharmacy costs, mean (SD)	$2,439 ($3,126)		$2,460 ($3,165)		0.1736	$2,446 ($3,139)
Median [range]	$1,809 [$4-$160,243]		$1,828 [$4-$121,051]			$1,816 [$4-160,243]

^aCalculated using an omnibus chi-square test for categorical variables, a t-test for continuous variables except costs, and a nonparametric test for costs. HMO = health maintenance organization; PPO = preferred provider organization; SD = standard deviation.