A comparison of diabetes medication adherence and healthcare costs in patients using mail order pharmacy and retail pharmacy

Figures & data

Figure 1. Cohort formation process for population of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

Figure 2. Selection process for population of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007 (f/u = follow-up).

Table 1.  Characteristics of cohort of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

	Total	Retail only	(%)	Mail order	(%)	Chi-sq
Index diabetes medication order (GPI 4 digit)
Amylin analogs (2715)	75	57	0.1	18	0.1
Incretin mimetic agents (2717)	700	456	1.0	244	1.7
Sulfonylureas (2720)	10,502	7613	17.4	2889	19.8
Amino acid derivatives (2723)	271	170	0.4	101	0.7
Biguanides (2725)	30,095	23,081	52.7	7014	48.0	<0.0001
Meglitinide analogues (2728)	260	162	0.4	98	0.7
Alpha-glucosidase inhibitors (2750)	88	47	0.1	41	0.3
Thiazolidinediones (2760)	8014	5595	12.8	2419	16.6
Combination products (2799)	8395	6619	15.1	1776	12.2
US census region
New England	1811	1301	3.0	510	3.5
Middle Atlantic	2950	1898	4.3	1052	7.2
South Atlantic	9448	6102	13.9	3346	22.9
East South Central	3870	2962	6.8	908	6.2
West South Central	13,348	10,682	24.4	2666	18.3	<0.0001
East North Central	8128	6835	15.6	1293	8.9
West North Central	9787	7761	17.7	2026	13.9
Mountain	2281	1724	3.9	557	3.8
Pacific	6384	4275	9.8	2109	14.4
Unknown	393	260	0.6	133	0.9
Diabetes complication severity index
0	43,642	33,111	75.6	10,531	72.1
1	8125	5889	13.4	2236	15.3
2	4260	3088	7.1	1172	8.0	<0.0001
3	1304	936	2.1	368	2.5
4 or more	1069	776	1.8	293	2.0
Additional characteristics related to adherence
Antidepressant agent use	13,408	9414		3994		<0.0001
Lipid lowering agent use	30,583	20,618		9965		<0.0001
Antihypertensive agent use	34,009	23,884		10,125		<0.0001
Diagnoses for depression	2633	1859		774		<0.0001

Table 2.  Characteristics of cohort of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

	Mean	95% CI lower	95% CI upper
Number of pre-index retail days
Retail	354.09	352.70	355.49
Mail	354.09	351.68	356.51
Number of follow-up days
Retail	453.64	452.50	454.79
Mail	546.98	545.00	548.96
Number of any pharmacy claims
Retail	17.86	17.78	17.94
Mail	14.55	14.41	14.68
Copayment for index diabetes medication
Retail	12.67	12.55	12.78
Mail	11.02	10.81	11.22
Charlson comorbidity index score
Retail	1.84	1.82	1.85
Mail	2.01	1.99	2.04
Age at index diabetes medication
Retail	50.16	50.08	50.25
Mail	52.46	52.31	52.60

Table 3.  Medication adherence data for cohort of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

	Total	Lower limit	Upper limit
Continuous MPR before change*
Retail	68.8%	68.5%	69.1%
Mail order	70.0%	69.5%	70.5%
Continuous MPR after change^†
Retail	63.4%	63.1%	63.7%
Mail order	84.8%	84.4%	85.1%

*Adjusting for: diabetes drug, total medication use, psychiatric diagnoses, medication copay, Charlston co-morbidity index, geography, age, anti-depressant use, lipid lowering use, anti-hypertensive use, and Diabetes complication and severity index.

^†Adjusting for: above and initial retail claim period MPR.

Table 4.  Differences in per member per month total healthcare expenditures for cohort of patients using mail order pharmacy for oral diabetes medications vs. retail in the MarketScan database between January 1, 2005 and December 31, 2007.

	PMPM Δ ($)	Lower limit ($)	Upper limit ($)
Total healthcare costs*
Period prior to change	(71.18)	(106.91)	(35.46)
Total follow-up after change	(34.32)	(57.89)	(10.76)
Total medical costs*
Period prior to change	(121.80)	(163.68)	(79.91)
Total follow-up after change	(37.54)	(55.53)	(19.55)
Total medication costs*
Period prior to change	26.82	19.07	34.57
Total follow-up after change	(7.45)	(20.13)	5.22
Diabetes-related healthcare costs*
Period prior to change	(20.10)	(30.72)	(9.48)
Total follow-up after change	6.22	0.04	12.40
Diabetes medical costs*
Period prior to change	(47.03)	(61.65)	(32.40)
Total follow-up after change	(19.14)	(25.16)	(13.11)
Diabetes medication costs*
Period prior to change	12.23	11.04	13.43
Total follow-up after change	14.13	12.35	15.91

*Adjusting for: Total MPR, initial retail claim period MPR, diabetes drug, total medication use, psychiatric diagnoses, medication copay, Charlston co-morbidity index, geography, age, anti-depressant use, lipid lowering use, anti-hypertensive use, and Diabetes complication and severity index.

Table 5.  Per member per month total healthcare expenditures for cohort of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

	PMPM ($)	Lower limit ($)	Upper limit ($)
Total healthcare costs*
Period prior to change
Retail	431.98	403.71	460.26
Mail order	360.80	313.67	407.93
Total follow-up after change
Retail	340.46	311.95	368.96
Mail order	306.13	265.61	346.66
Total medical costs*
Period prior to change
Retail	332.73	309.86	355.60
Mail order	210.94	158.83	263.04
Total follow-up after change
Retail	246.63	218.28	274.97
Mail order	209.09	169.42	248.75
Total medication costs*
Period prior to change
Retail	121.37	116.62	126.12
Mail order	148.20	138.26	158.13
Total follow-up after change
Retail	90.44	78.99	101.90
Mail order	82.99	61.39	104.60

*Adjusting for: total MPR, initial retail claim period MPR, diabetes drug, total medication use, psychiatric diagnoses, medication copay, Charlston co-morbidity index, geography, age, anti-depressant use, lipid lowering use, anti-hypertensive use, and Diabetes complication and severity index.

Table 6.  Per member per month diabetes-related healthcare expenditures for cohort of patients on oral diabetes medications in the MarketScan database between January 1, 2005 and December 31, 2007.

	PMPM ($)	Lower limit ($)	Upper limit ($)
Diabetes-related healthcare costs*
Period prior to change
Retail	94.41	86.78	102.04
Mail order	74.31	61.70	86.92
Total follow-up after change
Retail	97.92	90.59	105.26
Mail order	104.15	92.19	116.10
Diabetes-related medical costs*
Period prior to change
Retail	89.61	79.02	100.20
Mail order	42.58	23.75	61.42
Total follow-up after change
Retail	80.06	71.51	88.60
Mail order	60.92	48.60	73.24
Diabetes-related medication costs*
Period prior to change
Retail	26.85	26.13	27.58
Mail order	39.09	37.62	40.55
Total follow-up after change
Retail	22.78	20.21	25.36
Mail order	36.92	33.68	40.16

*Adjusting for: total MPR, initial retail claim period MPR, diabetes drug, total medication use, psychiatric diagnoses, medication copay, Charlston co-morbidity index, geography, age, anti-depressant use, lipid lowering use, anti-hypertensive use, and Diabetes complication and severity index.