Cannabis use in spinal cord injury
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ORIGINAL ARTICLE
Patterns of cannabis use in individuals with traumatic spinal cord injury in Denmark
Sven R. Andresen, MD1, Fin Biering-Sørensen, MD2, Ellen Merete Hagen, MD1,3,4, Jørgen F. Nielsen, MD5, Flemming W. Bach, MD6 and Nanna B. Finnerup, MD7
1Spinal Cord Injury Centre of Western Denmark, Department of Neurology, Regional Hospital of Viborg , Viborg, Denmark
2Clinic for Spinal Cord Injuries, Rigshospitalet, University of Copenhagen, Denmark
3Department of Clinical Medicine, University of Bergen, Norway
4The Autonomic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, University College London, UK
5Hammel Neurorehabilitation and Research Centre, Hammel, Denmark
6Department of Neurology, Aarhus University Hospital, Denmark
7Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Denmark
Short title: Cannabis use in spinal cord injury
1
Cannabis use in spinal cord injury
Abstract
Objective: To evaluate recreational and medical cannabis use in individuals with a traumatic spinal cord injury (SCI), including reasons and predictors for use, perceived benefits and negative consequences.
Design: Cross-sectional survey in Denmark.
Methods: 35-item questionnaire was sent to 1101 SCI patients having been in contact with a rehabilitation center between 1990-2012.
Results:537 participants completed the questionnaire. Of these, 36% had tried cannabis at least once and 9% were current users, of which 79% had started the use before the SCI. Main reason for use was pleasure, but 65% used cannabis partly for SCI-related consequences and 59% reported at least good effect on pain and spasticity. Negative consequences of use wereprimarily inertia and feeling quiet/subdued. Lower age, living in rural areas/larger cities, smoking, high alcohol intake and higher muscle stiffness weresignificantly associated with cannabis use. Those who had never tried cannabisreported they would mainly use cannabis to alleviate pain and spasticity if legalized.
Conclusion:Cannabis use is more frequent among SCI individualsthan the general population. High muscle stiffness and various demographic characteristics were associated with cannabis use. Most participants started using cannabis before the SCI, and there was considerable overlap between recreational and disability-related use.
Keywords: spinal cord injury;traumatic;pain; spasticity; cannabis;survey
J Rehabil Med
Correspondence address:
SR Andresen, Spinal Cord Injury Centre of Western Denmark, Department of Neurology
Regional Hospital of Viborg, HeibergsAllé 4
DK-8800 Viborg, Denmark
Tel: +45 7844 6156 or +45 7844 6150; fax: +45 7844 6159.
E-mail:
Introduction
Pain and spasticity are common sequelae of spinal cord injury (SCI), witharound 80% of SCI individuals reportingpainand 70% spasticity. Both conditions are often insufficiently treated and have a negative impact on the patients’ quality of life(1–4).
Cannabis is widely used for psychoactive and medical purposesbecause of its content of bioactive cannabinoids. The cannabinoid system plays a role in inhibiting synaptic transmission and controlling synaptic plasticity in pain and motor pathways through activation of the G-protein-coupled cannabinoid receptors CB1 and CB2.The two best studied constituents of cannabis are 9-Tetrahydrocannabinol (THC), with a preferential binding at CB1 receptors and high psychoactive effects and abuse potential, and cannabidiol (CBD), with limited psychoactive effects(5).Spinal cord injured individualshave in severalreportsclaimed that cannabis relieves their pain and spasticity(6–9), but our knowledgeof the extent and characteristics of cannabis consumption in the SCI population in Denmarkisinadequate.
Different studies in the general population and specific disease populations have found that anxiety, stress, pain, depression, nausea, appetite stimulation, sleep improvement, alleviation of muscle spasms, spasticity, facilitation of pleasure and partying are commonly given asreasons for using cannabis(10–13).Cannabis users more often smoked and drank alcohol than non-users and had more often tried cannabis in early adolescence, were younger, more often malesand had lower income and lower socioeconomic positionthan non-users(14,15).In individuals with HIV, lower income, tobacco smoking, ecstasy use and living in a rural areas residence were associated with cannabis use(12), while in a study in multiple sclerosis, smoking, greater disability by patients’own opinion (especially in lower limbs), marriage or beingin a stable relationshipwere associated with the useof cannabis(10).
The main purpose of this surveywas to evaluate the use of recreational and medical cannabis in a nationwide traumatic SCIpopulation, including predictors and reasons for use, benefits and negative consequences. A secondary purpose was to obtain knowledge on the prevalence, severity and impact of pain and spasticity.These results are reported elsewhere(16).
Methods
Study design
The study was an anonymous nationwide questionnaire study. Entry criteria were: age 18 years or over, acquired traumatic SCI and contact with one of the two SCI rehabilitation centers in Denmark (the Spinal Cord Injury Centre of Western Denmark and the Clinic for Spinal Cord Injuries) in the period from 1990 to 2012.The questionnaire was sent by postal service in January-April 2015 and participants had the option to completeeither a web-based questionnaire(via survey-xact.dk) or a paper-based questionnaire. All replies were anonymous as cannabis consumption is illegal in Denmark, and no reminders were sent out to non-responders.
Questionnaire
Data included demographic variables (age, gender, marital status, education level, region of residence with population density), labor force information (occupation, labor market affiliation, income) and lifestyle behaviors and habits (alcohol consumption, smoking)(17). Information about the participants’ spinal cord injuries included cause, year of injury, whether the participant was tetraplegic (arms, body and legs affected) or paraplegic(body and legs affected), had a complete (no sensation or voluntary muscular function below injury level) or incomplete (some sensation and muscular function below the injury level) injury(18)and to what level daily life was limited due to the SCI (”not at all”, ”little”, ”moderate” and ”much”).
Participants were asked if they had experienced continuous or daily recurring pain for more than 3 months. If participants answered ”yes” they were considered to have chronic pain and they were asked to complete the International SCI Pain Basic Data Set(19), which includesratingaverage pain intensityover the past 7 days on a 0-10 numeric rating scale (NRS).Pain treatment was recorded.Participants were also asked if they had experienced spasticity (muscle stiffness or spasms). Intensity of muscle stiffness was rated on an NRS (0-10) and the Penn Spasm Frequency Scale(20)was filled out. Spasticity treatment was determined using a list of treatment options.Quality of life was assessed using the International SCI Quality of Life Basic Data Set(21),where participants estimatedhow satisfied they had been with their life situation and physical and mental health in the past week using an NRS (0-10). Participants also rated sleep disturbances during the past week on an NRS (0-10).
Participants were asked if they had tried cannabis at some point in their lives. If not, they were asked if they would try it if it were legal and for what reason. Those who had tried or used cannabis one or more times were asked about their age of debut. They were also asked if they had tried it before and/or after their SCI, how many times they had tried or used it, in what form and the reason for using cannabis. Participants who had used cannabis within the last two years were defined as “current” cannabis users and were given further questions about frequency, quantity, cause and effect of their cannabis consumption, as well as the extent of negative consequences(12).
Statistical analysis
Data were described as mean (SD) or median (range) or frequency and percentages. Normality was checked using histograms and QQ-plots. Numerical data were analyzed using unpaired t-test or Mann-Whitney U-test.Categorical variables were analyzed with either Chi-square test or Fisher’s Exact test. The variables for which associations with current cannabis use in the univariate analyses were p<0.05 were included in a logistic regression model.A p-value less than 0.05 was considered statistically significant.Data missing in different variables were less than 2.4% and shown in result tables. Missing data were not replaced. Statistical analysis was performed with STATA release 12 (StataCorp, College Station, TX, USA).
Statement of ethics
We certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during the course of this research. The study was approved by the Danish Data Protection Agency, Copenhagen, Denmark (no. 1-16-02-210-14) and Danish Health and Medicines Authority, Copenhagen, Denmark (no. 3-3013-621/1).
Results
Participants
In the period from 1990 to 2012, 1371 individuals aged 18 years or over with an acquired traumatic SCI had been in contact with at least one of the two rehabilitation centers in Denmark. A total of 1101 individuals were sent the questionnaire (Fig. 1). The response rate was 49.4% (544 individuals), of which 196 responded via the web-based and 348 via the paper-basedquestionnaire. Of the returned questionnaires,7 were incomplete with no information on cannabis use, and they were therefore excluded. Consequently, we included and analyzed questionnaires from 537 individuals (Fig.1).
Demographics and clinical characteristics
Demographic variables and clinical characteristics are shown in Table I. Mean age was 54.6 (SD 14.6) years, range 18-88; 77% were men, and the majority livedwithout children either as married or in acohabiting relationship (41%) or alone (35%). The majority lived in small-to medium-sized cities, and 41% stated that they had at least a short post-secondary education. The majorityof participants were non-smokers and their alcohol consumption was within the guidelines for drinking alcohol set by the Danish Health and Medicines Authority(14 units for men and 7 units for women per week).The average time since injury was 18.2 (SD 12.8) years;46% of responders were tetraplegic, and 68% had an incomplete injury. The most common causes of injury were transportation(41%) and falls (30%) (Table I).Four hundredandtwelve participants (77%) reported that their SCI had at least moderate impact on their everyday life (Table I).Three hundred and ninety (73%)participants reported chronic pain. Of those reporting pain, the mean intensity(NRS, 0-10)was5.6 (SD 2.3) and 259 (67%) received treatment for pain. Spasticity was reported by 378 (71%) and 46% of these were in treatment for spasticity (Table I).
Cannabis use
Thirty-six percent (195 of 537) of all participants had tried cannabis at least once; of those 75% (147 of 195) were former cannabis users and 25% (48 of 195) current cannabis users (Table I). To be able to compare our data with available data on the general Danish population we divided the group by age. Of the 140 participants under the age of 45 years, 75 (53.6%) had tried cannabis at least oncein contrast to 120 (30.2%) of the 397 participants who were 45 years or older.The average age for trying cannabis for the first time was 20.4 (SD 9.1)years, range 8-72. Comparing current with former cannabis users, there was no difference (P=0.76). Of the 195 participants who had tried cannabis, 52% had used it before, 20% after and 28% both before and after their SCI. In the latter group, 53% reported that theirconsumptionhad decreased, 15% that it had increased and 32% that it was unchanged after their SCI. Of the 48 current cannabis users, 10 (21%) had tried cannabis after their SCI only.
Among participants who had tried cannabis, 174 (89%) stated they had tried it for pleasure, 42 (22%) for medicinal use in relation to their SCI (such as pain and spasticity), 8 (4%) for other medical reasons (depression, anxiety, stress, anorexia) and 17 (9%) gaveother reasons (sleep, sex, party and curiosity). Among the 145 former cannabis users, 38 (26%) had tried it more than 20 times, 17 (18%) 11-20 times and 90 (62%) l0 times or less. Former cannabis users most often used hashish, whereas current users more often usedother kinds of cannabis, containing more THC, including shit, hemp, skunk, pot and marihuana(Fig.2). Medical cannabis (sativex or dronabinol) was not commonly used (4 current and 3 former cannabis users). Of the 342 participants who had never tried cannabis, 69 (20%) responded that they would try it if it were legal and they reported pain, spasticity and sleep disturbance as the most common reasons(Fig. 3a).
Current cannabis users
Further details were obtained for the 48 current cannabis users, i.e. the participants who had used cannabis within the past two years. Thirty-one (65%) were under 45 years old. Twenty-two percent of the participants under 45 years and 4% of participants 45 years or olderwere current cannabis users.The average age of current users under 45 years were 34.9 (SD 7.2) years.Among the 48 current users, 14 reported daily use, 12 used at least once per week, 7 at least once per month, 10 at least once per year, and 5 used it less that once per year.Thirty-eight (79%) participants had tried it more than 20 times, 3 (6%) between 11 and 20 times and 7 (15%) l0 times or less. Among current cannabis users, 39 (81%) stated they had tried it for pleasure, 31 (65%) for medicinal use in relation to their SCI,7 (15%) for other medical reasons and 7 (15%) gave other reasons.Ten percent (5/48) of current cannabis users reported their use of cannabis for no other reason than for the secondary complications due to their SCI. Of the 31 participants who used it also for medical use in relation to their SCI, 8 started using cannabis after their SCI. The average intake the past 4 weeks among the 26 participants who were able to answer this question was 13.8 (SD 25.1) g and the average costs during the same period was 514.4 (SD 868.9) DKK, corresponding to approximately 69(SD 116.5) Euro. The most frequently reported reasons for using cannabis were pleasure followed by pain, party and spasticity (Fig. 3b). Most participants hada good to very good effect (Fig. 3b). For pain, 35% hada good and 24% avery good effect, and for spasticity, 32% had a good and 27% a very good effect. The 4 individuals who used medical cannabisreported none or some effect on pain and spasticity. 8.3 % (4 of 48) of current cannabis users used medical cannabis. Current cannabis users took paracetamol less often than participants who were not current cannabis users(P=0.030), while there was no significant difference between current and not-current cannabis users for other treatments for pain or spasticity(P>0.05).
Negative consequences of cannabis use included inertia, feeling quiet/subdued, absentmindedness and risky behavior, which were most often rated as slightly to moderately serious (Fig. 4).
Associations with current cannabis use
Significant variables identified through the univariate analyses inTable I were examined further using a logistic regression model. The overall model was significant (P<0.001) with an overall classification accuracy rate of 93%.Lower age, city population 5000 to 19999 and 100000, smoking, alcohol consumptionexceeding the recommended units per week and higher muscle stiffness scores were significantly associated with cannabis use (Table II).
DISCUSSION
In this nationwide questionnaire study in 537 individuals with SCI, 36% had tried cannabis at least once. Forty-eight participants (9%) had used cannabis within the past 2 years and were considered current users.This is lower than found in two previous studies in other disease populations. Harris et al.(12)found that 38.5% of participants with HIV/AIDS were current cannabis users, which was a 3.5 fold higher prevalence than in the general Canadian population.In a multiple sclerosis study in the UK(10), 18%of 254 responders were current cannabis users.Cannabis is legal for medical use in Canada, but not in the UK and Denmark, which may influencethe number of individuals using cannabis.
The Danish Health and Medicines Authority provides national data for the use of cannabis in individuals under 45 years(22). In our study, 54% (75/140) of participants under 45 yearshad tried cannabis at least once, and 22% (31/140) were current users compared to the general Danish population, of which 41.5% of individuals under the age of 45 years had tried cannabis at least once and 8.9%were current users, and 78% of current users were between 16 and 24 years(22).The Danish Health and Medicines Authority defined those who reported having used cannabis in the last year as current users(22),whereas in our study current users were defined as those who had used cannabis within the last 2 years. This maypartially explain why the number of currents users in this study is higher than in the general Danish population. Other reasons for the higher use among SCI individuals may be that cannabis use increases risk behavior and users thereforehave a greater risk of accidents and thus SCI. This is supported by the fact that 38 of the 48 current cannabis users started their cannabis use before their SCI. It is also likely that living with SCI and the consequent secondary complications maylead to increased cannabis use since 31 of the 48 current users reported that they used cannabis partly for relief of the secondary complications due to their SCI, although only 8of thesehad started using cannabis after their injury.