Prevalence and associated factors of the use of opioids in the treatment of chronic non-cancer pain. Perspective of the general Spanish population and the experience of patients.

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De Sola Perea, HelenaDate
2020-07-07Advisor
Failde, Inmaculada; Salazar, AlejandroDepartment
Biomedicina, Biotecnología y Salud PúblicaAbstract
Aims
The general aim of this thesis was to study the situation of opioid treatments for chronic noncancer pain (CNCP). The specific aims were: first, to determine and synthesize the prevalence of
the therapeutic use of opioids in patients with CNCP, and to analyze the factors associated with
their use through a systematic review of the literature and a meta-analysis; second, to
investigate the evolution of opioid-related mortality and potential years of life lost in the general
population in Spain from 2008 to 2017 and to compare the results by gender and age with the
United States; third, to describe the current perspective of the Spanish population toward opioid
use in the treatment of pain and to identify groups of individuals based on their point of view
on these drugs; and finally, to explore the experiences of patients with chronic non-malignant
low back pain in Spain undergoing long-term treatment (>3 months) with opioids.
Methods
In the first study of the thesis, a systematic review of the current literature and meta-analysis
were performed using two databases (PubMed and SCOPUS). For this purpose, original crosssectional studies published in English or Spanish between 2009 and 2019 with the main objective
of determining the prevalence of opioid use in CNCP patients were included. Search terms and
search strategies were adapted to each database. The articles included in the meta-analysis
were stratified according to the source of the sample, the type of pain, and the duration of the
opioid treatment.
The second paper of the thesis is a descriptive study using retrospective annual data from 2008
to 2017 in the general population of Spain and the United States. Information on the population
and opioid-related deaths stratified by age and sex was obtained from the Spanish National
Statistics Institute and from the Centers for Disease Control and Prevention (CDC) WONDER
Multiple Cause of Death Database, according to the ICD-10 codes. Years of life lost, crude and
standardized mortality rates were calculated and compared with the results in US.
The third article included in the thesis is a cross-sectional study carried out on a nationwide
representative sample of 1,299 Spanish adults. Data and information about beliefs, knowledge,
fears, opinions and, attitudes towards the use of opioids were collected via a computer assisted
telephone interview (CATI). A descriptive analysis of the variables studied and a cluster analysis
were performed to identify groups of people based on these parameters. In addition, a
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ABSTRACT. 18
multinomial logistic regression model was developed to analyze the variables related to the
clusters.
Finally, in the last part of the thesis, a qualitative study was performed using semi-structured
interviews. Recruitment and data collection were conducted from April to October 2018. Fifteen
participants were recruited from the Pain Clinic in Hospital Puerta del Mar. Inclusion criteria for
the study were: adults suffering from chronic non-malignant low back pain and receiving longterm treatment (>3 months) with opioids. We conducted interviews until very similar
experiences were described in the last interviews as in the previous ones. A constructionist
perspective was adopted. The interviews were analyzed by the qualitative content method
described by Graneheim and Lundman, and developed categories and themes discussed in the
light biomedicalization theoretical framework.
Results
In the first article, we identified that of the 1062 potential articles found in the systematic
review, 23 studies fulfilled the inclusion criteria. In the general population, the prevalence of
long-term (>3 months) opioid use was 2.3% (95%CI:1.5%-3.6%), the prevalence of short-term
opioid use was 7.3% (95%CI:4.3%-11.9%), and 5.8% among people with chronic low back pain
(95% CI:0.5% - 45.5%). The prevalence of opioid use among patients from the health records or
medical surveys was 41% (95%CI:23.3%-61.3%). Finally, in patients with musculoskeletal pain,
the prevalence was 20.5% (95%CI:12.9%-30.9%) and 24.5% among patients with fibromyalgia
(95%CI:22.9%-26.2%). A higher prevalence of opioid use was observed among the following
groups: men; younger people; patients receiving prescriptions of different types of drugs;
smokers and patients without insurance or with non-commercial insurance. In addition, nonwhite and Asian patients were less likely to receive opioids than non-Hispanic white patients.
The results of the second study showed that the crude rate of opioid-related deaths per 10^5
inhabitants has changed from 1.68 in 2008 to 2.25 in 2017 in Spain, with around 30,000 years of
life lost per year. The most affected groups were middle-aged men and women over 65, and the
main cause of death was accidental poisoning. The standardized rates per 10^5 inhabitants
across the years were between 1.19 and 1.62 in Spain and between 11.17 and 20.68 in the US
population.
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ABSTRACT. 19
In the analysis of the beliefs, fears, opinions and attitude towards opioids analyzed in the third
article in the general Spanish population, three groups of subjects were identified: a group with
a positive point of view (N=448) composed of people >65 years who would accept a treatment
if prescribed and were less fearful of these drugs; a group with a moderate point of view (N=337)
formed of younger subjects with university education, and who were better informed about
opioids, afraid of these drugs (OR=2.67), and more frequently associated them with drowsiness
(OR=2.58), nausea (OR=3.04), and tolerance (OR=2.16); a third group with a negative point of
view (N=468), with a lower educational level who would more often reject treatment with
opioids, and were more afraid of them (OR=3.95), considering that they may not be able to stop
the treatment (OR=3.04) and that the opioids may produce tolerance (OR=3.03).
Finally, in the analysis of the experiences of people with chronic pain (CP) taking opioids,
described in the fourth article, we developed one overarching theme - living with opioids:
dependence and autonomy while seeking relief - which crosscut three categories: 1) The long
pathway to opioids due to the invisibility of pain, 2) Opioids: from blind date to a long-term
relationship and 3) What opioids cannot fix. The results show that the long and difficult process
to obtain effective treatment was a fundamental part of the struggle to cope with pain, involving
long-term relationships with the health system. The two first categories refer to the journey
participants made to get a diagnosis and treatment with opioids, and their experiences during
this long and difficult process, which was quite unique for each person. The third category
describes the circumstances and situations experienced by the patients before and after the
painful episode started, and how these influenced the whole process.
Conclusions
The results obtained in the different studies lead to the following conclusions:
- The prevalence of opioid use in patients with CNCP varies depending on the duration
of treatment and the population analyzed, with higher prevalence in clinical studies
based on health registries and occasional users. Age, race, and the access to the
health service delivery system and its characteristics are the factors most related to
the use of opioids.
- Regarding opioid-related mortality, an opioid overuse crisis does not seem a likely
scenario in Spain. However, it is a social problem that requires special health
surveillance, particularly in middle-aged men and women over 65.
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ABSTRACT. 20
- The different perspectives of patients regarding the use of opioids to treat pain
should be taken into consideration by physicians when designing strategies to
inform patients about the treatment of pain with opioids. This should promote their
correct use, and prevent their misuse in particular.
- The experiences of patients should be considered to a greater extent by healthcare
professionals when giving information about opioids and setting treatment goals.
Greater consideration of the social determinants of health that affect chronic pain
experiences might lead to more effective solutions to chronic pain.
Subjects
Opioids; Chronic pain; Prevalence; Mortality; ExperiencesCollections
- Tesis [313]
- Tesis Bioq. Biol. [11]