Factors affecting medication adherence in elderly people

Figures & data

Table 1 Participant characteristics (n=160)

Variables	N	%a
Gender
Male	48	30.0
Female	112	70.0
Age, years (range 65–83), mean ± SD	67.9±3.94
65–74	145	90.6
≥75	15	9.4
Marital status
Single or never married	2	1.3
Married or cohabitating with someone	130	81.3
Widowed	23	14.4
Divorced or separated	5	3.1
Education
Elementary school or less	11	6.9
Middle school	42	26.3
High school	74	46.3
College level or more	33	20.6
Monthly allowance, US$
≤500	130	81.3
501–1,000	18	11.3
1,001–2,000	10	6.3
≥2,001	2	1.3
Health-related problemsb
Yes	130	81.3
No	30	18.8
Number of self-reported chronic diseases
0	30	18.8
1–3	120	75.0
≥4	10	6.3
Chronic conditionsc
Hypertension	68	42.5
Hypercholesterolemia	44	27.5
Diabetes	32	20.0
Heart disease	10	6.3
Bone fracture/osteoporosis	9	5.6
Number of prescription drugs currently taking
None	26	16.3
1	56	35.0
2	38	23.8
3	24	15.0
≥4	16	10.0
Frequency of doses
None	26	16.3
Once daily	70	43.8
Twice a day	35	21.9
≥Three times a day	29	18.1
Health literacy level
Inadequate (<6)	44	27.5
Adequate (≥6)	116	72.5
ARMS score (mean ± SD)d	20.45±5.21
<20	76	47.5
≥20	84	52.5

Notes:

a Because of rounding, percentages may not equal 100.

b Health-related problems were based on the individual’s current opinion of his or her health in comparison to 1 year previously.

c Participants were allowed to choose multiple answers.

d ARMS scores <20 indicate higher adherence, and scores ≥20 indicate lower adherence, respectively.

Abbreviations: ARMS, Adherence to Refills and Medications Scale; SD, standard deviation.

Table 2 Proportion of participants correctly answering the functional health literacy test items (n=160)

Items	Correct answers (%)
Numeracy	54.4a
How to take medication four times a day
Next medication time after the first medication at 7 am	34.4
Next medication time after the second medication	38.1
Last medication time	14.4
How to take medication before the expiration date
Checking the availability of medication in comparison to the expiration date	83.8
How to take medication every third day
Next medication day after taking medication on Tuesday	73.8
Comparing tested blood sugar levels with the normal range	59.4
How to take medication on an empty stomach
Medication time if it should be taken 1 hour before lunch	71.9
Medication time if it should be taken 2–3 hours after a meal	59.4
Reading comprehension	48.1b
Instruction for abdominal sonogram
What to take in the morning of the examination day	87.5
Time to take the exam	73.1
Where to go to find out the result	68.8
Informed consent document
Things to tell physician before the procedure	30.0
Procedure complications	12.5
Preventing falls
Reason for falls	38.1
Medications related to falls	26.9
Overall rate of correct answers	51.3
Total score, mean ± SD	7.72±3.51

Notes:

a The total average percentage of correct answers for the numeracy subtest.

b The total average percentage of correct answers for the reading comprehension subtest.

Abbreviation: SD, standard deviation.

Table 3 Patient factors, medication factors, and health care provider factors by medication adherence levela

Variables	Adherence levelb			P-valuec
	Total (N=160)	Low (n=84)	High (n=76)
Patient factors
Age, years (range 65–83), n (%)				0.309
65–74	145 (90.6)	78 (92.9)	67 (88.2)
≥75	15 (9.4)	6 (7.1)	9 (11.8)
Gender, n (%)				0.782
Male	48 (30.0)	26 (31.0)	22 (28.9)
Female	112 (70.0)	58 (69.0)	54 (71.1)
Education, n (%)				0.188
Elementary school or less	11 (6.9)	8 (9.5)	3 (3.9)
Middle school	42 (26.3)	26 (31.0)	16 (21.1)
High school	74 (46.3)	34 (40.5)	40 (52.6)
College level or more	33 (20.6)	16 (19.0)	17 (22.4)
Health-related problems, n (%)				0.187
Yes	130 (81.3)	19 (22.6)	11 (14.5)
No	30 (18.8)	65 (77.4)	65 (85.5)
Number of self-reported chronic diseases, n (%)				0.338
None	30 (18.8)	19 (22.6)	11 (14.5)
1–3	120 (75.0)	61 (72.6)	59 (77.6)
≥4	10 (6.3)	4 (4.8)	6 (7.9)
Expectancy of treatment, n (%)				0.007d
Negative	7 (4.4)	6 (7.1)	1 (1.3)
Neutral	52 (32.5)	34 (40.5)	18 (23.7)
Positive	101 (63.1)	44 (52.4)	57 (75.0)
Health literacy level, n (%)				0.304
Inadequate (<6)	44 (27.5)	26 (31.0)	18 (23.7)
Adequate (≥6)	116 (72.5)	58 (69.0)	58 (76.3)
Medication factors
Number of prescription drugs currently taking, n (%)				0.724
None	26 (16.3)	15 (17.9)	11 (14.5)
1	56 (35.0)	27 (32.1)	29 (38.2)
2	38 (23.8)	18 (21.4)	20 (26.3)
3	24 (15.0)	14 (16.7)	10 (13.2)
≥4	16 (10.0)	10 (11.9)	6 (7.9)
Pharmacy use patterns, n (%)				0.271
Single pharmacy use	79 (49.4)	38 (45.2)	41 (53.9)
Multiple pharmacy use	81 (50.6)	46 (54.8)	35 (46.1)
Cost-related nonadherence, n (%)				0.094
Yes	20 (12.5)	14 (16.7)	6 (7.9)
No	140 (87.5)	70 (83.3)	70 (92.1)
Health care provider factors
Satisfaction with patient counseling, n (%)				0.000
Dissatisfaction	27 (16.9)	23 (27.4)	4 (5.3)
Neutral	74 (46.3)	41 (48.8)	33 (43.4)
Satisfaction	59 (36.9)	20 (23.8)	39 (51.3)
Patient–pharmacist relationship and communication, n (%)				0.017
Poor	20 (12.5)	15 (17.9)	5 (6.6)
Neutral	74 (46.3)	42 (50.0)	32 (42.1)
Good	66 (41.3)	27 (32.1)	39 (51.3)
Explanation of medication, n (%)				0.003
None	10 (6.3)	10 (11.9)	0 (0.0)
A little	85 (53.1)	46 (54.8)	39 (51.3)
Enough	65 (40.6)	28 (33.3)	37 (48.7)

Notes:

a Because of rounding, percentages may not equal 100.

b Participants were divided by adherence level as high adherence (ARMS score <20; n=76, 47.5%) and low adherence (ARMS score ≥20; n=84, 52.5%).

c P-values were based on chi-square tests of each characteristic by levels of medication adherence, and a P-value <0.05 indicates a statistically significant difference between groups.

d Fisher’s exact test (two-tailed).

Abbreviation: ARMS, Adherence to Refills and Medications Scale.

Table 4 Factors influencing medication adherencea

Variables	R	R^2	Adjusted R^2	B	SE	β	t	P-value
Constant	0.554	0.307	0.270	35.057	6.614		5.300	0.000
Age (years)				0.019	0.091	0.014	0.208	0.835
Education level				−0.895	0.443	−0.153	−2.020	0.045
Health-related problems (1= yes)b				−3.178	1.087	−0.239	−2.923	0.004
Health literacy				−0.017	0.116	−0.011	−0.144	0.886
Frequency of doses				0.963	0.404	0.189	2.381	0.018
Satisfaction with patient counseling				−1.334	0.576	−0.215	−2.316	0.022
Patient–pharmacist relationship and communication				0.022	0.671	0.003	0.033	0.974
Explanation of medication				−2.945	0.711	−0.335	−4.144	0.000

Notes:

a Dependent variable was ARMS scores and lower scores indicated better adherence.

b Dummy coded.

Abbreviations: SE, standard error; ARMS, Adherence to Refills and Medications Scale.