Concordance between two methods in measuring treatment adherence in patients with type 2 diabetes

Figures & data

Figure 1 Treatment adherence according to prescription refill.

Table 1 Medication use and treatment adherence by prescription refill

	Antidiabetic drugs	Antihypertensive drugs	Lipid-lowering drugs	Global
Type of treatment n (%)	305 (95.3)	257 (80.3)	201 (62.8)	319 (99.7)
Mean treatment adherence (SD) (n)	85.5 (29.9) (285)	88.59 (27.6) (252)	85.4 (32.9) (196)	85.61 (27.0) (317)

Abbreviation: SD, standard deviation.

Table 2 Descriptive analysis of the baseline characteristics of the sample according to treatment adherence as determined by prescription refill

	Global TA		P-value
	Good TA (n=221)	Poor TA (n=96)
	n (%)	n (%)
Age (<70 years)	113 (51.1)	68 (70.8)	0.001
Sex (females)	113 (51.1)	36 (37.5)	0.028
Marital status
Single	11 (5.0)	2 (2.1)	0.459
Married	135 (61.1)	63 (65.6)
Separated/divorced	12 (5.4)	7 (7.3)
Widowed	58 (26.2)	20 (20.8)
Not declared	5 (2.3)	4 (4.2)
Free pharmacy service	188 (85.1)	61 (63.5)	<0.001
Smoking
Nonsmoker	130 (58.8)	41 (42.7)	<0.001
Smoker	21 (9.5)	25 (26.0)
Ex-smoker	65 (29.4)	25 (26.0)
Not declared	5 (2.3)	5 (5.2)
Obesity/overweight	157 (71.0)	63 (65.6)	0.137
Arterial hypertension	185 (83.7)	74 (77.1)	0.057
Dyslipidemia	170 (76.9)	76 (79.2)	0.720
Impaired renal function	65 (29.4)	32 (33.3)	0.646
Ischemic heart disease	40 (18.1)	10 (10.4)	0.095
Stroke	27 (12.2)	8 (8.3)	0.435
Peripheral artery disease	26 (11.8)	15 (15.6)	0.365
Diabetic retinopathy	47 (21.3)	14 (14.6)	0.092
Nephropathy	64 (29.0)	31 (32.3)	0.583
Psychiatric disorders	84 (38.0)	32 (33.3)	0.279
	Mean (SD)	Mean (SD)
Years of DM2	11.03 (7.20)	8.99 (5.77)	0.008
Number of chronically prescribed drugs per patient	7.53 (3.36)	6.05 (3.49)	<0.001
Number of visits in the last year
Physician	10.50 (6.44)	9.75 (5.53)	0.320
Nurse	10.03 (7.63)	7.72 (7.14)	0.012

Abbreviations: DM2, type 2 diabetes mellitus; SD, standard deviation; TA, treatment adherence.

Table 3 Treatment adherence according to the H–S test and the prescription refill

	H–S test		κ	P-value
	Good TA	Poor TA
Adherence to antidiabetic drugs, n (%) (n=252)
Good TA	158	20	0.011	0.834
Poor TA	65	9
Adherence to antihypertensive drugs, n (%) (n=231)
Good TA	158	14	0.109	0.056
Poor TA	49	10
Adherence to lipid-lowering drugs, n (%) (n=182)
Good TA	111	11	0.012	0.830
Poor TA	54	6
Global adherence, n (%) (n=282)
Good TA	187	19	0.081	0.118
Poor TA	64	12

Abbreviations: H–S, Haynes–Sackett; TA, treatment adherence; κ, Kappa.

Table 4 Mean values of the risk factor control indicators in relation to treatment adherence

	Good TA	Poor TA	P-value
HbA1c (%), mean (SD) (n)
Antidiabetic use	6.76 (1.38) (n=179)	7.21 (1.64) (n=88)	0.020
Total drug use	6.69 (1.27) (n=211)	7.33 (1.73) (n=87)	0.002
Haynes–Sackett test	6.75 (1.33) (n=238)	7.19 (1.55) (n=30)	0.095
SBP, mean (SD)
DBP, mean (SD)
Antihypertensive drug use	135.53 (15.16) (n=177)	137.27 (13.84) (n=63)	0.423
	74.36 (8.79) (n=177)	76.97 (9.15) (n=63)	0.046
Total drug use	134.65 (15.0) (n=215)	134.51 (14.12) (n=85)	0.941
	74.55 (8.7) (n=215)	76.81 (8.83) (n=85)	0.045
Haynes–Sackett test	134.66 (14.71) (n=242)	131.94 (10.79) (n=31)	0.320
	74.82 (8.91) (n=242)	77.55 (8.91) (n=31)	0.102
LDLc, mean (SD)
Lipid-lowering drug use	105.08 (31.04) (n=119)	114.91 (38.95) (n=57)	0.099
Total drug use	108.94 (30.04) (n=200)	118.71 (34.08) (n=1)	0.018
Haynes–Sackett test	110.92 (31.98) (n=228)	114.55 (34.16) (n=29)	0.568

Abbreviations: DBP, diastolic blood pressure; HbA_1c, glycosylated hemoglobin; LDLc, low-density lipoprotein cholesterol; SBP, systolic blood pressure; SD, standard deviation; TA, treatment adherence.

Table 5 Multivariate logistic regression analysis for the identification of predictors of good treatment adherence referred to antidiabetic, antihypertensive, and lipid-lowering drugs

	OR	95% CI
Antidiabetic drugs (n=285)
Free pharmacy service	2.60	1.47–4.62
Antihypertensive drugs (n=252)
Comorbidities	2.10	1.04–4.27
Lipid-lowering drugs (n=196)
Female physician	5.45	2.09–14.16
Prior ischemic heart disease	3.80	1.54–9.38
Years of professional experience	1.15	1.06–1.26
Years with the same patient quota	0.85	0.76–0.95

Abbreviations: CI, confidence interval; OR, odds ratio.