Antidepressants in primary care: patients’ experiences, perceptions, self-efficacy beliefs, and nonadherence

Figures & data

Figure 1 Illustration of three-step method to assess efficiently a comprehensive list of side effects.

Table 1 Demographic and clinical characteristics of the participants (n=225)

Variables	Statistic
Demographic characteristics
Women, n (%)	149 (66)
Mean age, years (SD)	51.1 (13.5)
Married or living together, n (%)	176 (78)
Higher educated (vs low to medium), n (%)	57 (25)
Clinical characteristics
Status of use, n (%)
Starters and recent users <3 months	18 (8)
Users >3 months	183 (81)
Stoppers	24 (11)
Duration of use (only users >3 months), n (%)
0–1 years	26 (14)
1–4 years	37 (20)
4 years or longer	120 (66)
Type of antidepressant, n (%)
TCA	38 (17)
SSRI	137 (61)
Othera	50 (22)
Indication for use, n (%)
Depression	134 (60)
Anxiety or panic	103 (46)
Otherwise	82 (36)
Ever been admitted to psychiatric hospital/ward, n (%)	14 (6)
Additional treatment with psychotherapy, n (%)	84 (37)

Note:

a Includes serotonin–norepinephrine reuptake inhibitors and tetracyclic antidepressants.

Abbreviations: SD, standard deviation; TCA, tricyclic antidepressants; SSRI, selective serotonin reuptake inhibitor; vs, versus.

Table 2 Experiences and perceptions with regard to the efficacy of antidepressants

		Disagree and neutral		Agree
		n	%	n	%
1.	The use of antidepressants is necessary for me	64	28	161	72
2.	I am convinced of the efficacy of antidepressants	73	32	152	68
3.	I have doubts about the efficacy of antidepressants	193	86	32	14
4.	Antidepressants have a limited efficacy	152	68	73	32
5.	I expect antidepressants to help	68	30	157	70
6.	I know how antidepressants work	80	36	145	64
7.	I received information about how antidepressants work	65	29	160	71
8.	I know why I have to use antidepressants	25	11	200	89
9.	I am using antidepressants, because I was afraid my complaints would come back	102	45	122	55
10.	Antidepressants prevent my complaints from coming back	92	41	133	59
11.	Using antidepressants resolves your problems	151	67	74	33
12.	The longer you use antidepressants, the better they work	164	73	61	27
13.	It took a long time, before my antidepressants worked	154	69	70	31
14.	Owing to antidepressants, I have more energy	140	62	84	37
15.	Owing to antidepressants, I sleep better	128	57	96	43
16.	Because of my antidepressants, I feel physically better	109	48	115	51
17.	Because of my antidepressants, I feel mentally better	60	27	164	73

Table 3 Worries about and experiences of side effects of antidepressants

Side effects	Worry about side effects		Experiences of side effects
	Yes, n (%)	M level of worry (SD)a	Yes, n (%)	M level of bother (SD)a
Side effects associated with antidepressants
Dizziness	40 (18)	2.8 (1.2)	16 (7)	4.1 (1.1)
Vomiting/feeling nauseous	9 (4)	2.6 (1.3)	6 (3)	4.2 (1.0)
Gastrointestinal complaints	37 (16)	2.6 (1.4)	23 (10)	4.6 (0.8)
Dry mouth	53 (24)	2.3 (1.3)	50 (22)	3.7 (1.2)
Sweating	55 (24)	2.7 (1.2)	42 (19)	4.4 (0.7)
Emotional flatness	54 (24)	3.1 (1.2)	42 (19)	4.1 (1.1)
Insomnia	23 (10)	3.3 (1.2)	29 (13)	4.5 (0.8)
Drowsiness	50 (22)	3.5 (1.2)	36 (16)	4.1 (1.0)
Tiredness	68 (30)	3.3 (1.3)	52 (23)	4.3 (0.9)
Libido decrease	95 (42)	3.4 (1.3)	84 (37)	4.2 (1.1)
Decreased erection or ejaculation	33 (15)	3.5 (1.1)	28 (12)	3.3 (1.1)
Other side effects
Memory, concentration or tiredness
Forgetfulness			42 (19)	4.4 (0.8)
Diminished concentration			37 (16)	4.4 (0.6)
Gynecological complaints
Painful or sensitive breasts			8 (4)	3.8 (1.0)
Vaginal discharge, vaginal dryness, or vaginal itch			11 (5)	3.9 (1.0)
Hot flushes			18 (8)	4.1 (0.9)
Vaginal blood loss			1 (0.4)	5 (NA)
Emotional
Feeling restless			33 (15)	4.6 (0.6)
Skin or hair
Hair loss			15 (7)	4.0 (0.9)
Rash			12 (5)	4.5 (0.5)
Heart, vessels, or bladder
Heart palpitations			16 (7)	4.3 (0.9)
Edema			16 (7)	4.4 (0.8)
Urinary retention			8 (4)	3.8 (1.6)
Incontinence			14 (6)	4.5 (0.9)
Gastrointestinal problems
Stomach ache, stomach cramps, heartburn, or bloating			28 (12)	4.4 (0.6)
Muscles, bones, or joints
Ache, stiffness, swelling, or inflammation of joints			34 (15)	4.4 (0.7)
Trembling			17 (8)	4.2 (0.9)
Backache			23 (10)	4.5 (0.7)
Muscular pain or muscle cramps			33 (15)	4.4 (0.8)

Note:

a Assessed on a scale ranging from 1 to 5.

Abbreviations: SD, standard deviation; NA, not available; M, mean.

Table 4 Experiences of practical problems of antidepressant use

Practical problems	Yes, n (%)	M level of bother (SD)g
Information,a intake of tablets,b and packaging and blisterc	62 (28)	3.5 (0.9)
Logistical problemsd	47 (21)	3.6 (1.0)
Limitations in daily lifee	46 (20)	2.9 (0.9)
Medication interactionf	50 (22)	3.0 (1.1)

Notes:

a Contradictory, redundant, small font size, text comprehension

b tablets – how to take, number of tablets in blister impractical, needed to be broken for correct dose, were difficult to break or to swallow, taste, took a long time to get correct dose, use difficult to fit into daily routine, dose skipping

c unclear label, difficulties regarding opening package, pressing tablets out of blister or cutting part of blister, changes of package, medicine name change, tablet color/form

d antidepressants unavailable or unclear how to get refills, getting insufficient antidepressant tablets, having to go too often to pharmacist or physician

e whether antidepressant use permitted alcohol consumption and affected driving ability negatively

f medicine interactions

g assessed on a scale ranging from 1 to 5.

Abbreviation: SD, standard deviation; M, mean.

Table 5 Multivariate logistic regression results: associations of unintentional and intentional nonadherence with patients’ experiences and perceptions with regard to antidepressant use

Predictors	Nonadherence
	Unintentional	Intentional	MPR
	Odds ratio (95% CI)	Odds ratio (95% CI)	Odds ratio (95% CI)
Age	0.95 (0.91–0.99)†
Marital status
Not married/divorced/widow(er)	Reference
Married/living together	1.2 (0.4–4.2)
Duration of use			1.9 (1.04–3.5)*
Overall efficacy score	0.99 (0.92–1.06)
Convinced of efficacy score		0.9 (0.8–0.96)†
Number of side effects experienced			0.9 (0.7–1.0)
Emotional side effects
No	Reference	Reference
Yes	1.4 (0.5–4.2)	1.8 (0.9–4.0)
Number of practical problems experienced	1.3 (1.1–1.7)*	1.1 (0.9–1.3)
Taking self-efficacy (MUSE)	0.7 (0.5–0.9)†
Learning self-efficacy (MUSE)	1.2 (0.8–1.7)

Notes:

* P<0.05

† P<0.01.

Abbreviations: MPR, medication possession ratio; CI, confidence interval; MUSE, Medication Understanding and Use Self-Efficacy Scale.

Table S1 Items to assess experiences and perceptions with regard to the efficacy of antidepressants

Items, and their factor loadings		Factor dimensions
All items scored on 5-point scales: 0, fully disagree; 4, fully agree		Ia	IIb	IIIc	IVd
1.	The use of antidepressants is necessary for me	0.66	0.38	0.21	0.12
2.	I am convinced of the efficacy of antidepressants	0.72	0.33	0.21	0.16
3.	I have doubts about the efficacy of antidepressants†	0.82	0.02	0.03	0.19
4.	Antidepressants have a limited efficacy†,**	0.45	−0.35	0.15	0.15
5.	I expect antidepressants to help	0.64	0.36	0.15	0.19
6.	I know how antidepressants work	0.13	0.76	0.12	0.13
7.	I received information about how antidepressants work	0.18	0.67	0.06	0.12
8.	I know why i have to use antidepressants	0.42	0.64	0.14	−0.03
9.	I am using antidepressants, because I was afraid my complaints would come back	−0.13	0.27	0.59	0.22
10.	Antidepressants prevent my complaints from coming back	0.47	0.35	0.50	0.09
11.	Using antidepressants resolves your problems	0.28	−0.03	0.70	0.09
12.	The longer you use antidepressants, the better they work	0.18	0.04	0.67	0.05
13.	It took a long time before my antidepressants worked†,*	−0.05	0.05	−0.11	−0.05
14.	Owing to antidepressants, I have more energy	0.15	0.21	0.27	0.75
15.	Owing to antidepressants, I sleep better**	0.14	−0.04	−0.06	0.78
16.	Because of antidepressants, I feel physically better	0.33	0.18	0.35	0.57
17.	Because of my antidepressants, I feel mentally better***	0.51	0.24	0.27	0.44
% of variance explained		34%	9%	7%	6%
Cronbach’s alpha		0.84	0.69	0.62	0.78

Notes:

a Convinced of efficacy

b education about efficacy

c prevention of relapse

d symptomatic efficacy

* did not load on any of the four factors

** alpha improved after deletion of this item

*** thought to reflect the fourth dimension to a greater extent than the first dimension from a theoretical point of view

† reversed scoring, higher score now indicates more positive perceptions.

Table S2 Items to assess unintentional and intentional nonadherence

Factor loadings of nonadherence items		Nonadherence dimensions
		Unintentional	Intentional
MMAS items
1.	Do you sometimes forget to take your antidepressants? (0, no; 1, yes)	Excludeda
2.	Over the past 2 weeks, were there any days when you did not take your antidepressants? (0, no; 1, yes)	0.41	0.34
3.	Have you ever cut back or stopped taking your antidepressants without telling your doctor, because you felt worse when you took them? (0, no; 1, yes)	−0.07	0.58
4.	When you travel or leave home, do you sometimes forget to bring along your antidepressants? (0, no; 1, yes)	0.58	0.09
5.	Did you take your antidepressants yesterday?† (0, yes; 1, no)	0.16	0.26
6.	When you feel like your symptoms are under control, do you sometimes stop taking your antidepressants? (0, no; 1, yes)	0.13	0.61
7.	Taking medication everyday is a real inconvenience for some people. Do you ever feel hassled about sticking to your antidepressant-treatment plan? (0, no; 1, yes)	0.43	0.22
8.	How often do you have difficulty remembering to take all your antidepressants? (0, never or seldom; 1, once in a while; 2, sometimes; 3 most of the time; 4, always)	0.81	0.00
MARS items (all items: 0, never; 1, seldom; 2, sometimes; 3, often; 4, always)
1.	I forget to use my antidepressants	0.70	0.18
2.	I adjust the dosage of my antidepressants	0.04	0.67
3.	I stop using antidepressants for a while	0.08	0.69
4.	I decide to skip an antidepressant’s dose	0.35	0.43
5.	I take fewer antidepressant tablets than prescribed to me	0.07	0.61
Additional items
1.	I sometimes forgot to take my antidepressants (0, no; 1, yes)	0.87	−0.09
2.	I forgot whether I had already taken my antidepressants (0, no; 1, yes)	Excludedb
3.	I intend to use antidepressants in the way prescribed (0, fully agree; 4, fully disagree)	0.11	0.50
4.	I intend to discontinue using antidepressants prematurely† (0, fully disagree; 4, fully agree)	−0.12	0.40
% of variance explained		23%	16%
Cronbach’s alpha		0.71	0.73

Notes:

† Reversed scoring, higher score now indicates more nonadherence

a duplicate

b redundant. Items were excluded from the total score if they were duplicate items, had low or ambiguous factor loadings, or improved Cronbach’s alpha after deletion. The final calculation of the total scores was as follows: intentional nonadherence = MMAS i3 + MMAS i5 + MMAS i6 + MARS i2 + MARS i3 + MARS i4 + MARS i5 + additional i3 + additional i4; unintentional nonadherence = MMAS i2 + MMAS i4 + MMAS i7 + MMAS i8 + MARS i1 + additional i1.

Abbreviations: MMAS, Morisky Medication Adherence Scale; MARS, Medication Adherence Rating Scale; i, self-evident.