Medication adherence in chronic illness: do beliefs about medications play a role?

Figures & data

Figure 1 The theorized model of the relationships between beliefs about medications and medication adherence, controlling for patient background variables; hypothesized correlations are omitted from the figure for simplicity.

Table 1 Descriptive statistics for the scales used, alpha reliability coefficients, and Cronbach’s alpha when items were deleted

Scales and items	Mean	SD	Corrected item–total correlation	Cronbach’s alpha if item deleted
MARS-5 (Cronbach’s alpha = 0.822)	20.72	4.056
MA1: I forget to take my medicine	3.67	1.188	0.588	0.797
MA2: I change the dose of my medicine	4.36	0.990	0.610	0.788
MA3: I stop taking my medicine for a while	4.10	1.107	0.657	0.773
MA4: I decide to miss out a dose of my medicine	4.19	1.028	0.678	0.768
MA5: I take less of my medicine than instructed	4.40	0.982	0.552	0.804
BMQ-Harm (Cronbach’s alpha = 0.736)	10.75	3.044
BG2: people who take medicines should stop their treatment for a while every now and again	2.66	1.084	0.442	0.728
BG3: most medicines are addictive	2.81	1.051	0.591	0.638
BG5: medicines do more harm than good	2.58	0.950	0.549	0.665
BG6: all medicines are poisons	2.70	0.985	0.537	0.671
BMQ-Overuse (Cronbach’s alpha = 0.330)	13.62	2.388
BG1: doctors use too many medicines	3.13	1.169	0.231	0.189
BG4: natural remedies are safer than medicines	3.47	1.042	0.171	0.271
BG7: doctors place too much trust on medicines	3.72	0.803	0.086	0.350
BG8: if doctors had more time with patients they would prescribe fewer medicines	3.30	1.092	0.197	0.238
BMQ-Benefit (Cronbach’s alpha = 0.541)	14.77	2.257
BG9: medicines help many people to live better lives	3.93	0.822	0.406	0.405
BG10: in the future medicines will be developed to cure most diseases	3.93	0.798	0.318	0.478
BG11: in most cases the benefits of medicines outweigh the risks	3.63	0.840	0.294	0.497
BG12: medicines help many people to live longer	3.28	1.005	0.306	0.497
SS (Cronbach’s alpha = 0.566)	14.96	2.837
SS1: my body is very sensitive to medicines	2.88	1.057	0.416	0.451
SS2: my body overreacts to medicines	3.56	0.855	0.094	0.623
SS3: I usually have stronger reactions to medicines than most people	3.07	0.853	0.323	0.512
SS4: I have had a bad reaction to medicines in the past	2.71	0.986	0.317	0.515
SS5: even very small amounts of medicines can upset my body	2.75	0.927	0.495	0.408

Note: The bold distinguishes statistics related to the total scale as opposed to statistics related to particular items.

Abbreviations: MARS, Medication Adherence Report Scale; BMQ, Beliefs about Medication Questionnaire; SS, sensitive soma.

Table 2 Standardized item ladings from exploratory (principal component) factor analysis resulting in six-factor solution

Scales and items	Factors
	1	2	3	4	5	6
MARS-5	0.713
I forget to take my medicine	0.748
I change the dose of my medicine	0.769
I stop taking my medicine for a while	0.807
I decide to miss out a dose of my medicine	0.704
I take less of my medicine than instructed	0.713
BMQ-Harm
BG2: people who take medicines should stop their treatment for a while every now and again	−0.326	0.551
BG3: most medicines are addictive		0.747
BG5: medicines do more harm than good		0.618	0.345
BG6: all medicines are poisons		0.649
BMQ-Overuse
BG1: doctors use too many medicines		0.538
BG4: natural remedies are safer than medicines		0.602			−0.395
BG7: doctors place too much trust on medicines				0.521	0.453
BG8: if doctors had more time with patients they would prescribe fewer medicines				0.737
BMQ-Benefit
BG9: medicines help many people to live better lives					0.626
BG10: in the future medicines will be developed to cure most diseases				0.545
BG11: in most cases the benefits of medicines outweigh the risks				0.428
BG12: medicines help many people to live longer					0.794
SS
SS1: my body is very sensitive to medicines			0.787
SS2: my body over-reacts to medicines						0.799
SS3: I usually have stronger reactions to medicines than most people						0.805
SS4: I have had a bad reaction to medicines in the past			0.676
SS5: even very small amounts of medicines can upset my body		0.333	0.673
Cumulative % variance explained after extraction	14.1%	26.2%	35.1%	42.7%	49.8%	56.6%

Notes: Table values are varimax-rotated factor loadings. Factor loadings <0.3 are not presented in the table. The bold is to emphasize that loading such items are acceptable to count together for a unique factor.

Abbreviations: MARS, Medication Adherence Report Scale; BMQ, Beliefs about Medication Questionnaire; SS, sensitive soma.

Figure 2 Structural equation model of adherence as a function of negative beliefs toward medications and background variables.

Notes: χ² = 68.319 (df = 36, n = 783; p = 0.001), CFI = 0.981, RMSEA = 0.034, and SRMR = 0.026. All paths are statistically significant at p < 0.05. Paths representing effects of background variables are drawn in thinner lines. Illness severity = z-score of comorbidity + z-score of number of medications.
Abbreviations: BG, belief-general; SS, sensitive soma; MA, medication adherence; RMSEA, root mean square error of approximation; CFI, comparative fit index; SRMR, standardized root mean square residual.

Table 3 Demographic characteristics (N = 783)

Characteristics	n	%
Gender
Male	444	56.7
Female	339	43.3
Age, years
18–39	191	24.4
40–49	236	30.1
50–59	219	28.0
60 or more	137	17.5
Marital status
Single	81	10.3
Married	577	73.7
Divorced	51	6.5
Widowed	74	9.5
Nationality
Kuwaiti	366	46.7
Non-Kuwaiti	417	53.3
Monthly income
<KD 1,000	387	49.4
KD 1,000–1,500	191	24.4
KD 1,500–2,000	92	11.7
≥KD 2,000	105	13.4
Missing	8	1.0
Education
Less than high school	168	21.5
High school	142	18.1
Some college	151	19.3
University	248	31.7
Graduate degree	74	9.5
Employment
Retired	120	15.3
Unemployed	140	17.9
Employed part time	70	8.9
Employed full time	453	57.9
Governorate
Capital	200	25.5
Farwanya	183	23.4
Alahmadi	136	17.4
Hawalli	153	19.5
Aljahra	111	14.2

Abbreviation: KD, Kuwaiti Dinars.

Table 4 Self-reported disease conditions and number of medications (N = 783)

Characteristics	n	%
Disease categoriesa
CVD	628	80.2
DM	530	67.7
Respiratory disease	190	24.3
Mood disorder	224	28.6
Comorbidity mean ± SD (range)	2.0 ± 0.9 (0–4)
One disease category	222	28.4
Two disease categories	345	44.1
Three disease categories	164	20.9
Four disease categories	42	5.4
Noneb	10	1.3
Medications mean ± SD (range)	4.0 ± 2.6 (1–18)
One medication	115	14.7
Two medications	129	16.5
Three medications	154	19.7
Four medications	118	15.1
Five and six medications	162	20.7
Seven or more medications	105	13.4

Notes:

a A “yes” on one or more of 18 listed conditions; 11 for CVD, two for DM, two respiratory diseases, and three for mood disorder (other options were: “no”, “sometimes”, and “I don’t know”).

b Had no “yes” on any of the 18 listed conditions.

Abbreviations: CVDs, cardiovascular diseases; DM, diabetes mellitus.