Associations between adherence and outcomes among older, type 2 diabetes patients: evidence from a Medicare Supplemental database

Figures & data

Figure 1 Inclusion–exclusion criteria and sample size.

Notes: Identification window defined as July 1, 2010 through June 30, 2011. Index date defined as first receipt of GLA in identification window. Preperiod defined as 1 year prior to index date. Postperiod defined as 3 years plus index date.
Abbreviations: GLA, glucose-lowering agent; T2D, type 2 diabetes.

Table 1 Descriptive statistics

Variable	N or mean	% or SD
Patient characteristics – defined at index date
Age (mean; SD)	74.42	6.23
Sex
Male	65,103	52.83
Female	58,132	47.17
Region
Northeast	18,568	15.07
North Central	46,777	37.96
South	32,745	26.57
West	25,145	20.40
Insurance plan type
Comprehensive insurance	63,486	51.52
Exclusive provider organization	49	0.04
Health maintenance organization	18,490	15.00
Point of service	4,949	4.02
Preferred provider organization	35,982	29.20
CDHP/HDHP	279	0.23
General health and comorbidities in preperiod
Charlson Comorbidity Index (mean; SD)	2.44	1.81
Diabetes Complications Severity Index (mean; SD)	1.47	1.64
Anxiety	2,529	2.05
Depression	4,922	3.99
Hyperlipidemia	40,138	32.57
Provider and prescriber visited in preperiod
Cardiologist	37,015	30.04
Endocrinologist	7,457	6.05
Family medicine	61,177	49.64
Internal medicine	58,528	47.49
Renal dialysis therapy	103	0.08
Medication use in first 3 months of postperiod
Insulin	14,498	11.76
Number of non-insulin classes (mean; SD)	1.38	0.72
Number of non-antidiabetic medications (mean; SD)	6.14	3.50
Outcomes in postperiod
Drug costs (mean; SD)	$12,456	13,732
Acute-care costs (mean; SD)	$16,674	42,810
Outpatient costs (mean; SD)	$18,904	43,633
Total costs (mean; SD)	$48,034	71,392
Diabetes-related drug costs (mean; SD)	$3,432	4,470
Diabetes-related acute-care costs (mean; SD)	$6,319	20,434
Diabetes-related outpatient costs (mean; SD)	$3,523	8,607
Diabetes-related total costs (mean; SD)	$13,274	23,902
Adherence in first year of postperiod
PDC (mean; SD)	75.97	27.48
PDC quintiles
<20%	9,539	7.74%
≥20%–<40%	7,148	5.80%
≥40%–<60%	10,591	8.59%
≥60%–<80%	18,188	14.76%
≥80%	77,769	63.11%

Abbreviations: CDHP, consumer-directed health plan; HDHP, high-deductible health plan; PDC, proportion of days covered; SD, standard deviation.

Figure 2 All-cause costs: by adherence levels.^a

Note: ^at-Tests comparing component costs across alternative thresholds were all statistically significant (P<0.05).

Figure 3 Diabetes-related costs: by adherence levels.^a

Note: ^at-Tests comparing component costs across alternative thresholds were all statistically significant (P<0.05) except: diabetes-related total costs with adherence level 60%–<80% compared to adherence level ≥80%.

Table 2 Resource utilization and complications: by adherence levelsa

Outcome	PDC <20%		PDC ≥20%–<40%		PDC ≥40%–<60%		PDC ≥60%–<80%		PDC ≥80%
	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Probability of hospitalization (%)	56.22	16.28	50.05	15.56	45.45	15.44	41.44	14.93	37.43	13.77
Probability of ER visit (%)	72.09	13.23	66.58	13.48	62.40	14.07	58.57	14.29	54.18	13.85
Number of hospitalizations	1.26	0.86	0.99	0.61	0.83	0.51	0.71	0.43	0.60	0.33
Number of ER visits	3.37	2.40	2.57	1.64	2.16	1.37	1.82	1.12	1.50	0.85
Hospital LOS	8.71	7.15	6.19	4.62	4.84	3.55	3.82	2.78	3.00	1.97
Probability of acute complication (%)	24.11	13.86	18.19	10.48	16.26	9.71	14.47	8.92	13.02	8.17

Note:

a t-Tests comparing resource utilization and complications across alternative thresholds were all statistically significant (P<0.001).

Abbreviations: ER, emergency room; LOS, length of stay; PDC, proportion of days covered; SD, standard deviation.