Non-Adherence to Pharmacotherapy: A Prospective Multicentre Study About Its Incidence and Its Causes Perceived by Chronic Pain Patients

Figures & data

Figure 1 Flowchart of the study design and follow-up times.

Table 1 Sociodemographic Characterization of the Patients (n=562)

Sex, n (%)
Male	175 (31.1)
Female	387 (68.9)
Age
Range (years)	19-96
Mean (SD)	58.6 (14.2)
Years, n (%)
18–24	5 (0.9)
25–34	18 (3.2)
35–44	76 (13.5)
45–54	121 (21.5)
55–64	136 (24.2)
65–74	125 (22.2)
≥ 75	81 (14.4)
Household, n (%)
Alone	51 (9.1)
Husband/wife/partner	230 (40.9)
Husband/wife/partner and children	173 (30.8)
Son/daughter	40 (7.1)
Nursing home/local institutions	1 (0.2)
Other	67 (11.9)
Education Level, n (%)
None	15 (2.7)
Elementary (1–4 years)	283 (50.4)
High School
5–9 years (basic)	124 (22.1)
10–12 years (secondary)	54 (9.6)
College degree	65 (11.6)
Master/PhD	7 (1.2)
Other	14 (2.5)
Professional Situation, n (%)
Employee	140 (24.9)
Full-time self-employed	29 (5.2)
Part-time self-employed	9 (1.6)
Unemployed with experience	67 (11.9)
Unemployed with no experience	2 (0.4)
Student	4 (0.7)
Housewife	25 (4.4)
Retired	255 (45.4)
Other	31 (5.5)
Job impairment n (%)	295 (52.5)
Job loss	50 (16.9)
Change of work	1 (0.3)
Change of responsibilities	26 (8.8)
Early retirement	50 (16.9)
Sick leave (>3 months)	70 (23.7)
Other	98 (33.2)
Family Support, n (%)
Yes	432 (76.9)
No	130 (23.1)

Table 2 Clinical Characterization of the Patients (n=562)

International Classification of Chronic Pain, n (%)
Musculoskeletal	311 (55.3)
Neuropathic	126 (22.4)
Oncologic	97 (17.3)
Post-chirurgic or post-traumatic	71 (12.6)
Primary	38 (6.8)
Visceral	17 (3.0)
Headache and orofacial	8 (1.1)
Single diagnostic category	453 (81.0)
Two diagnostic categories	103 (18.4)
Neuropathic+ Musculoskeletal	38 (6.8)
Post-chirurgic or post-traumatic+ Musculoskeletal	9 (9.6)
Oncologic + Musculoskeletal	16 (2.9)
Oncologic + Post-chirurgic or post-traumatic	15 (2.7)
Primary+ Musculoskeletal	14 (2.5)
Oncologic+ Neuropathic	12 (2.1)
Three diagnostic categories	3 (0.5)
History of Pain (years)
Range	0-66
Mean (SD)	8.9 (12.4)
Brief Pain Inventory (BPI), mean (SD)
Pain severity	5.7 (1.9)
Pain interference	6.1 (2.4)
Body Mass Index (BMI), n (%)
Range	13.8–45.2
Mean (SD)	26.7 (4.9)
≤18.4 (underweight)	21 (4.2)
18.5–24.9 (normal weight)	170 (33.7)
25–29.9 (pre-obesity)	203 (40.3)
30–34.9 (Obesity class I)	81 (16.1)
35–39.9 (Obesity class II)	23 (4.6)
≥40 (Obesity class III)	6 (1.2)

Figure 2 Evolution of the non-adherence along 1-year treatment (n=562).

Table 3 Comparison Between Adherent and Non-Adherent Patients, Concerning Self-Rated Adherence (MARS), Emotional State (HADS) and Pain (BPI) at the Time Points Evaluated

	Baseline	T7Days			T6m			T12m		p
		Non-Adherents 201 (36.8%)	Adherents 345 (63.2%)	p	Non-Adherents 257 (47.4%)	Adherents 285 (52.6%)	p	Non-Adherents 276 (51.0%)	Adherents 265 (49.0%)
MARS, median (P25-P75) [Maximum, Minimum]	n.a.	44 (36.5–45)[14–45]	45 (45–45)[27–45]	<0.001^Ŧ	44 (40–45)[13–45]	45 (41.2–45)[16–45]	<0.001Ŧ	44 (39–45)[17–45]	45 (40–45)[23–45]	<0.001Ŧ
Intentional Non-adherence	n.a.	43.9 (36–45)[10–45]	45 (45–45)[25–45]	<0.001Ŧ	45 (40.5–45)[9–45]	45 (41.2–45)[12–45]	<0.001Ŧ	45 (38.3–45)[13–45]	45 (39.4–45)[20–45]	<0.001Ŧ
Unintentional Non-adherence	n.a.				45 (45–45)[9–45]	45 (45–45)[9–45]	0.148Ŧ	44 (45–45)[9–45]	45 (45–45)[18–45]	0.246Ŧ
^aSometimes,^Citation3 n(%)		9 (5.3%)	2 (0.6%)	<0.002Ŧ
^aRarely,^Citation4 n(%)		11 (6.4%)	15 (4.5%)
^aNever,^Citation5 n(%)		151 (88.3%)	317 (94.9%)
HADS - Anxiety, n (%)
Normal	176 (31.3)	70 (35.0)	95 (27.6)	0.085Ɨ	81 (31.5)	87 (30.5)	0.792Ɨ	88 (31.9)	73 (27.8)	0.569Ɨ
Borderline	112 (19.9)	50 (25.0)	79 (23.0)		66 (25.7)	68 (23.9)		59 (21.4)	58 (22.1)
Clinical	247 (48.8)	80 (40.0)	170 (49.3)		110 (42.8)	130 (45.6)		129 (46.7)	132 (50.2)
HADS - Depression, n (%)
Normal	250 (44.5)	39 (19.6)	106 (30.9)	0.011Ɨ	78 (30.7)	94 (33.3)	0.706Ɨ	92 (33.6)	69 (26.0)	0.055Ɨ
Borderline	94 (16.7)	59 (29.6)	98 (28.6)		72 (28.3)	82 (29.1)		70 (25.5)	90 (34.0)
Clinical	218 (38.8)	101 (50.8)	139 (40.5)		104 (40.9)	106 (37.6)		112 (40.9)	106 (40.0)
BPI, mean (sd)
Pain Severity	5.7 (1.9)	4.9 (2.2)	5.3 (2.1)	0.083*	4.8 (2.4)	4.9 (3.2)	0.773*	5.0 (2.5)	5.0 (2.8)	0.609*
Pain Interference	6.1 (2.4)	4.8 (2.4)	5.0 (2.5)	0.506*	4.5 (2.8)	4.9 (2.8)	0.178*	4.9 (2.8)	5.1 (2.6)	0.609*

Notes: *p value for t-test, ^Ɨp value for Chi-square tests, ^Ŧp value for Mann-Whitney test. ^aAt T7, the results of Unintentional Non-adherence are presented in Likert values because of the continuity of scale could not be assumed, as more than 90% of the results are in the value of 5 (never).

Abbreviations: P25-P75, 25th percentile and 75th percentile (representing the interquartile range); sd, standard deviation; n.a., not applicable.

Figure 3 Percentages of “non-adherence reasons” by ACT groups and their significant associations.

Abbreviations: NAO, Narcotic Analgesics (Opioids); ATE, Antiepileptics and anticonvulsants; ATD, Antidepressants; ANG, Analgesics antipyretics; TOG, Topical non-steroidal anti-inflammatory drugs; NSAID, Non-steroidal anti-inflammatory drugs; OM, Other Medications.

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