Development and evaluation of the Measure of Drug Self-Management

Figures & data

Table 1 Characteristics of study sample

Variable, n (%)	Participants (n=193)
Age, mean (range)	61.1 (28–94) years
Female	116 (60.1%)
Race/ethnicity
African American	104 (54.4)
White	83 (43.0)
Other	5 (2.6)
Educational attainment
Some high school or less	37 (19.2)
12th grade or GED	73 (37.8)
Some college	45 (23.3)
College graduate or more	37 (19.2)
Do not know/refused	1 (0.5)
Income
<$10,000	39 (20.2)
$10,000–$19,999	60 (31.1)
$20,000–$29,999	26 (13.5)
≥$30,000	58 (30.0)
Do not know/refused	10 (5.2)
Literacy skills
Limited	27 (14.0)
Marginal	67 (34.7)
Adequate	99 (51.3)

Note: All currencies are in US$.

Abbreviation: GED, General Educational Development diploma.

Table 2 Item analysis of final scale (n=179)

	Mean	Item-total correlation coefficient	Cronbach’s α if item is deleted
1. Did you forget to take your (insert drug name) at any time last week?	0.82	0.47	0.68
2. In the past month have you stopped taking (insert drug name) for any reason without telling your doctor?	0.90	0.31	0.71
3. I often forget to take my medicine.	0.58	0.39	0.70
4. I am organized about when and how I take my medicines.	0.77	0.45	0.69
5. I have a hard time paying for my medicines.	0.61	0.19	0.72
6. The print instructions on my prescription bottles are confusing.	0.91	0.29	0.71
7. Having to take medicines worries me.	0.80	0.35	0.70
8. I often have a hard time remembering if I have already taken my medicine.	0.81	0.38	0.70
9. I do not take my medicines when I am feeling sad or upset.	0.91	0.39	0.69
10. My medicines disrupt my life.	0.93	0.31	0.71
11. When my medicine causes minor side effects, I stop taking it.	0.68	0.38	0.70
12. The idea of taking medications for the rest of my life makes me very uncomfortable.	0.73	0.31	0.71

Table 3 Internal consistency, construct validity, and predictive validity for the Measure of Drug Self-Management

Internal consistency		Construct validity	Predictive validity
		Correlation (P-value)	Correlation (P-value)
Cronbach’s α	Item-total correlation range	Morisky Medication Adherence Scale	HbA1C	Systolic BP	Diastolic BP	LDL levels
0.72	0.19–0.47	−0.62 (<0.001)	−0.07 (0.35)	−0.09 (0.19)	−0.18 (0.01)	−0.27 (<0.001)

Abbreviations: BP, blood pressure; LDL, low-density lipoprotein

Figure S1 Measure of Drug Self-Management (MeDS).