Effectiveness of mailed letters to improve medication adherence among Medicare Advantage Plan participants with chronic conditions

Figures & data

Figure 1 Customer selection flowchart.

Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker.

Table 1 Linear regression analysis of change in 6-month PDC before vs after the mailed letter

	Beta (standard error)	P-value
Language of letter	−0.050 (0.048)	0.299
Age	−0.004 (0.002)	0.041
Gender	−0.044 (0.037)	0.238
Ethnicity	−0.019 (0.023)	0.410
Region	0.027 (0.029)	0.342
Low income subsidy eligibility	0.024 (0.040)	0.553
Medication category	0.010 (0.026)	0.693
Generic vs brand	0.033 (0.086)	0.701
Day supply	0.123 (0.039)	0.002
Copay	−0.002 (0.002)	0.180
Pharmacy type	0.020 (0.121)	0.872

Abbreviation: PDC, proportion of days covered.

Table 2 Logistic regression analysis of adherence defined as 6-month PDC of at least 80% after the mailed letter

	OR (95% CI)	P-value
Language of letter
English	Reference	Reference
Spanish	0.739 (0.383–1.426)	0.368
Age
Age, years	0.994 (0.972–1.016)	0.594
Gender
Female	Reference	Reference
Male	0.968 (0.615–1.524)	0.888
Ethnicity
White	Reference	Reference
Hispanic	0.673 (0.323–1.402)	0.291
African-American	1.008 (0.538–1.888)	0.981
Asian	1.049 (0.185–5.937)	0.957
Region of Texas
Out of Texas	Reference	Reference
West	1.359 (0.338–5.471)	0.666
East	1.563 (0.401–6.091)	0.520
Low income subsidy eligibility
No	Reference	Reference
Yes	1.189 (0.725–1.951)	0.492
Medication category
Statin	Reference	Reference
ACEI/ARB	0.649 (0.396–1.061)	0.085
Oral antidiabetic	0.777 (0.406–1.489)	0.447
Generic vs brand
Generic	Reference	Reference
Brand	0.773 (0.262–2.281)	0.641
Day supply
30 days or less	Reference	Reference
>30 days	2.198 (1.307–3.696)	0.003
Copay
Copay, $	0.994 (0.973–1.016)	0.587
Pharmacy type
Retail	Reference	Reference
Mail order	1.028 (0.254–4.159)	0.969
Initial PDC
PDC	39.283 (2.764–558.363)	0.007

Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; PDC, proportion of days covered.

Table 3 Baseline Medicare Advantage Plan participant and medication characteristicsa

	n (%)	Not adherent at final, n (%)	Adherent at final, n (%)	P-value
Language of letter				0.216b
English	362 (78.7)	270 (74.6)	92 (25.4)
Spanish	98 (21.3)	79 (80.6)	19 (19.4)
Age				0.676c
Age, years	70.0±10.5	70.1±10.7	69.6±9.9
Gender				0.784b
Female	231 (50.2)	174 (75.3)	57 (24.7)
Male	229 (49.8)	175 (76.4)	54 (23.6)
Ethnicity				0.602b
White	307 (66.7)	232 (75.6)	75 (24.4)
Hispanic	66 (14.4)	54 (81.8)	12 (18.2)
African-American	80 (17.4)	58 (72.5)	22 (27.5)
Asian	7 (1.5)	5 (71.4)	2 (28.6)
Region				0.576b
Out of Texas	16 (3.5)	13 (81.3)	3 (18.8)
West Texas	221 (48.1)	171 (77.4)	50 (22.6)
East Texas	223 (48.5)	165 (74.0)	58 (26.0)
Low Income subsidy eligibility				0.575b
No	222 (48.3)	171 (77.0)	51 (23.0)
Yes	238 (51.7)	178 (74.8)	60 (25.2)
Medication category				0.223b
Statin	196 (42.6)	141 (71.9)	55 (28.1)
ACEI/ARB	189 (41.1)	150 (79.4)	39 (20.6)
Oral antidiabetic	75 (16.3)	58 (77.3)	17 (22.7)
Generic vs brand				0.655b
Generic	431 (93.7)	326 (75.6)	105 (24.4)
Brand	29 (6.3)	23 (79.3)	6 (20.7)
Day supply				0.013b
30 days or less	170 (37.0)	140 (82.4)	30 (17.7)
>30 days	290 (63.0)	209 (72.1)	81 (27.9)
Copay				0.782c
Copay, $	4.36±12.64	4.45±13.41	4.07±9.89
Pharmacy type				0.805b
Retail	449 (97.6)	341 (76.0)	108 (24.1)
Mail order	11 (2.4)	8 (72.7)	3 (27.3)
Initial PDC				0.013c
PDC	0.51±0.11	0.51±0.12	0.54±0.09

Notes:

a Values represent mean ± SD for age, copay, and initial PDC.

b Chi-squared test.

c t-Test.

Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; PDC, proportion of days covered.

Table 4 PDC rates and adherence dataa

Total sample		Participants with one or more medication fill after the letter was sent
Total letters (n)	460	Total letters (n)	284
Initial PDC (mean ± SD)	0.51±0.11	Initial PDC (mean ± SD)	0.52±0.11
Final PDC (mean ± SD)	0.41±0.39	Final PDC (mean ± SD)	0.67±0.28
Change in PDC (mean ± SD)	−0.10±0.40	Change in PDC (mean ± SD)	0.15±0.28
Adherent at final, n (%)		Adherent at final, n (%)
No	349 (75.9)	No	60.9 (173)
Yes	111 (24.1)	Yes	39.1 (111)
Filled after letter, % (n)		Days before next fill
No	38.5 (176)		39.01
Yes	61.7 (284)		42.58

Note:

a Values represent mean ± SD for initial PDC, final PDC, change in PDC, and days before next fill.

Abbreviation: PDC, proportion of days covered.

Table S1 Sub-analysis of letter recipients with medication filled after letter was sent (n=284)

Linear regression analysis of change in PDC – change in 6-month PDC from before the mailed letter to after the mailed letter
	Beta (standard error)	P-value
Language of letter	−0.009 (0.044)	0.834
Age	−0.001 (0.002)	0.478
Gender	−0.001 (0.033)	0.980
Ethnicity	−0.030 (0.021)	0.153
Region: Texas vs out of state	0.045 (0.022)	0.045
Low income subsidy eligibility	0.043 (0.037)	0.251
Medication category	−0.007 (0.022)	0.755
Generic vs brand	−0.060 (0.077)	0.436
Day supply	0.144 (0.034)	<0.001
Copay	−0.001 (0.003)	0.802
Pharmacy type	0.032 (0.104)	0.762

Abbreviation: PDC, proportion of days covered.

Table S2 Sub-analysis of letter recipients with medication filled after letter was sent (n=284)

Logistic regression analysis of adherence as measured by 6-month PDC of at least 80% after the mailed letter
	OR (95% CI)	P-value
Language of letter
English	Reference	Reference
Spanish	0.948 (0.418–2.148)	0.898
Age
Age, years	1.001 (0.975–1.028)	0.939
Gender
Female	Reference	Reference
Male	1.045 (0.604–1.811)	0.874
Ethnicity
White	Reference	Reference
Hispanic	0.642 (0.266–1.553)	0.326
African-American	0.743 (0.344–1.603)	0.449
Asian	–	0.987
Region of Texas
Out of Texas	Reference	Reference
West	0.524 (0.088–3.142)	0.480
East	0.912 (0.181–4.603)	0.911
Low income subsidy eligibility
No	Reference	Reference
Yes	1.667 (0.888–3.130)	0.112
Medication category
Statin	Reference	Reference
ACEI/ARB	0.777 (0.425–1.422)	0.413
Oral antidiabetic	0.743 (0.341–1.619)	0.455
Generic vs brand
Generic	Reference	Reference
Brand	0.305 (0.081–1.147)	0.079
Day supply
30 days or less	Reference	Reference
>30 days	2.743 (1.514–4.970)	0.001
Copay
Copay, $	1.021 (0.981–1.064)	0.303
Pharmacy type
Retail	Reference	Reference
Mail order	0.845 (0.154–4.649)	0.847

Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; PDC, proportion of days covered.