Clinical outcome data of chronic pain patients treated with cannabis-based oils and dried flower from the UK Medical Cannabis Registry

Figures & data

Figure 1. Flowchart of data inclusion and completeness of follow-up.

Table 1. Patient demographics, clinical history, and prescriptions.

Baseline Characteristics	No. (%)/Mean ± SD/Median [IQR]
Prescription information
Oils	348 (45.7)
CBD, mg/24 h	20.0 [20.0–30.0]
THC, mg/24 h	10.0 [10.0–20.0]
Dried flower	36 (4.7)
CBD, mg/24 h	2.5 [0.0–5.0]
THC, mg/24 h	125.0 [100.0–196.3]
Oils and dried flower	377 (49.5)
CBD, mg/24 h	20.0 [20.0–25.0]
THC, mg/24 h	120.0 [110.0–205.0]
Gender
Female	401 (52.7)
Male	360 (47.3)
Age, years	46.8 ± 15.4
Body mass index*, kg/m2	27.7 ± 7.0
Occupation
Unemployed	273 (35.9)
Undisclosed	211 (27.7)
Professional	73 (9.6)
Managers	46 (6.0)
Other occupations	45 (5.9)
Elementary occupations	32 (4.2)
Technicians and associate professionals	31 (4.1)
Craft and related trades workers	16 (2.1)
Service and sales workers	15 (2.0)
Clerical support workers	13 (1.7)
Plant and machine operators and assemblers	3 (0.4)
Armed forces	2 (0.3)
Skilled agricultural, forestry and fishery workers	1 (0.1)
Cannabis status
Current user	326 (42.8)
Cannabis naïve	313 (41.1)
Ex-user	122 (16.0)
Cannabis use, gram years	6.0 [1.9–20.0]
Smoking status
Ex-smoker	310 (40.1)
Nonsmoker	255 (33.5)
Current smoker	196 (25.8)
Smoking pack years	10 [5.0–20.0]
Weekly alcohol consumption, units	0 [0.0–5.0]
Charlson Comorbidity Index	1.0 [0.0–6.0]

Data on patients prescribed cannabis-based medicinal products (CBMP) for chronic pain was recorded by clinicians. Cannabis naïve users had never used cannabis before,©and ex-users had previously used cannabis but were not using it at the time of their prescription. Current users were using nonprescription cannabis at the time of their prescription. Median cannabis use in gram years for ex- and current users was calculated as previously described38. *n = 615. CBD = cannabidiol, THC = (-)-trans-Δ9-tetrahydrocannabinol. SD = standard deviation, IQR = interquartile range.

Table 2. Paired baseline and follow-up data for pain-specific patient-reported outcome measures (PROMs).

PROM	Follow-up interval	n	Baseline scores [IQR]	Scores at follow-up [IQR]	P-value
Oils
P-VAS	1 month	242	7.00 [6.00–8.00]	7.00 [5.00–8.00]	<0.001***
	3 months	134	7.00 [6.00–8.00]	6.00 [4.00–7.00]	<0.001***
	6 months	68	7.00 [6.00–8.00]	6.00 [3.00–7.25]	<0.001***
BPI – Interference Score	1 month	247	6.57 [5.14–8.00]	5.86 [3.64–7.36]	<0.001***
	3 months	134	6.29 [4.71–7.57]	5.29 [3.43–6.82]	<0.001***
	6 months	68	5.86 [4.14–7.00]	4.71 [3.14–6.43]	<0.010**
BPI – Severity Score	1 month	247	6.00 [4.75–7.25]	5.50 [4.00–6.75]	<0.001***
	3 months	134	5.88 [4.25–7.00]	5.00 [3.75–6.19]	<0.001***
	6 months	68	5.75 [4.25–7.00]	5.00 [2.94–6.25]	<0.001***
MPQ2	1 month	243	4.13 [2.93–5.65]	3.67 [2.32–4.96]	<0.001***
	3 months	134	3.98 [2.71–5.44]	2.89 [1.79–4.81]	<0.001***
	6 months	68	3.76 [2.80–4.99]	2.66 [1.63–3.84]	<0.001***
Dried flower
P-VAS	1 month	22	7.00 [5.25–7.75]	5.50 [3.00–6.75]	<0.010**
	3 months	17	7.00 [5.00–7.00]	5.00 [3.00–7.00]	<0.050**
	6 months	7	5.00 [3.00–7.50]	3.00 [1.50–5.00]	0.370
BPI – Interference Score	1 month	23	5.71 [4.79–7.21]	5.14 [2.21–5.93]	<0.010**
	3 months	17	5.71 [3.71–7.29]	4.14 [2.43–6.29]	0.210
	6 months	7	3.71 [1.64–4.79]	2.14 [1.50–3.64]	0.160
BPI – Severity Score	1 month	23	5.50 [3.63–6.75]	5.25 [2.88–5.63]	<0.050**
	3 months	17	6.00 [3.75–7.00]	5.00 [3.25–5.50]	<0.050**
	6 months	7	3.75 [3.25–5.38]	3.25 [1.38–4.75]	0.380
MPQ2	1 month	22	3.96 [1.77–5.45]	2.55 [1.26–3.90]	<0.010**
	3 months	17	4.69 [1.54–5.60]	2.38 [0.88–3.52]	<0.010**
	6 months	7	1.54 [1.39–1.81]	0.54 [0.35–1.44]	0.071
Oils and dried flower
P-VAS	1 month	270	7.00 [6.00–8.00]	6.00 [5.00–7.75]	<0.001***
	3 months	183	7.00 [6.00–8.00]	6.00 [4.00–7.00]	<0.001***
	6 months	78	7.00 [5.00–8.00]	5.00 [3.00–7.00]	<0.001***
BPI – Interference Score	1 month	274	7.00 [5.57–8.43]	5.79 [3.57–7.43]	<0.010**
	3 months	183	6.57 [5.29–8.07]	5.00 [2.86–6.93]	<0.001***
	6 months	78	6.07 [4.00–7.54]	4.50 [2.64–6.64]	<0.001***
BPI – Severity Score	1 month	274	5.75 [5.00–7.00]	5.25 [3.75–6.50]	0.070
	3 months	183	5.50 [4.50–6.88]	4.75 [3.00–6.25]	<0.001***
	6 months	78	5.13 [3.75–6.00]	4.50 [3.00–5.94]	<0.010**
MPQ2	1 month	271	4.56 [3.27–6.20]	3.83 [1.98–5.37]	<0.001***
	3 months	183	4.19 [3.01–5.92]	3.33 [1.37–4.93]	<0.001***
	6 months	78	3.88 [2.59–5.65]	2.89 [1.39–4.81]	<0.001***

Chronic pain patients treated with cannabis-based medicinal products recorded pain-specific PROMs at regular follow-up intervals. Paired data©were analyzed with a Wilcoxon rank-sum test. Median and interquartile ranges (IQR) are shown. P-VAS = Pain Visual©Analog Scale, BPI = Brief Pain Inventory Short-Form, MPQ2 = McGill Pain Questionnaire-2 Short-Form. A lower score indicates reduced pain. * p < 0.050, ** p < 0.010, *** p < 0.001.

Table 3. Multivariate analysis of variables affecting BPI Severity scores.

Variable	Odds Ratio [95% Confidence Interval]	P-value
Age, years
18–30	-	Ref
31–40	1.282 [0.268–6.122]	0.756
41–50	2.025 [0.468–8.752]	0.345
51–60	0.808 [0.181–3.613]	0.780
61–70	1.419 [0.288–6.996]	0.667
71–80	1.616 [0.230–11.354]	0.629
81+	N/A
BMI, kg/m2
<20	0.296 [0.066–1.325]	0.111
20–25	-	Ref
25–30	0.897 [0.318–2.533]	0.838
30–35	0587 [0.187–1.844]	0.362
35+	0.869 [0.128–5.892]	0.885
Cannabis status
Current users	-	Ref
Ex-users	1.555 [0.392–6.129]	0.532
Naïve	1.063 [0.390–2.896]	0.905
Gender
Female	-	Ref
Male	0.609 [0.258–1.437]	0.258
Treatment type
Oils	-	Ref
Oils and dried flower	1.359 [0.506–3.650]	0.543
Dried flower	2.115 [0.278–16.112]	0.470

A multivariate binary logistic regression model was used to assess the effect of age, body mass index (BMI), prior cannabis experience, gender, and treatment type on Brief Pain Inventory (BPI) Severity scores after 6 months relative to baseline. The BPI Severity score measures patient pain severity.

Table 4. Paired baseline and follow-up data for non-pain-specific patient-reported outcome measures (PROMs).

		Oils				Dried flower
PROM	Follow-up interval	n	Baseline scores [IQR]	Scores at follow-up [IQR]	P-value	n	Baseline scores [IQR]	Scores at follow-up [IQR]	P-value
SQS	1 month	250	4.00 [3.00–6.00]	6.00 [4.00–7.00]	<0.001***	23	5.00 [3.00–6.00]	7.00 [3.50–8.00]	0.030*
	3 months	135	5.00 [3.00–6.00]	6.00 [4.00–8.00]	<0.001***	17	5.00 [2.00–7.00]	7.00 [6.00–8.00]	0.011*
	6 months	68	6.00 [3.00–6.00]	6.00 [4.00–8.00]	0.014*	7	7.00 [4.00–8.00]	7.00 [7.00–8.50]	0.160
GAD-7	1 month	252	6.00 [1.75–11.00]	4.00 [0.75–8.00]	<0.001***	23	4.00 [1.50–7.50]	3.00 [0.00–6.50]	0.200
	3 months	135	6.00 [2.00–10.50]	4.00 [0.00–7.00]	<0.001***	17	6.00 [1.00–8.00]	3.00 [0.00–5.00]	0.070
	6 months	68	5.00 [1.75–8.00]	4.00 [0.00–6.25]	0.088	7	1.00 [0.50–5.00]	0.00 [0.00–3.50]	0.052
EQ-5D-5L Index	1 month	250	0.33 [0.12–0.59]	0.54 [0.31–0.65]	<0.001***	23	0.55 [0.28–0.72]	0.74 [0.59–0.77]	0.034*
	3 months	135	0.43 [0.18–0.62]	0.56 [0.33–0.69]	<0.001***	17	0.58 [0.26–0.74]	0.65 [0.50–0.84]	0.010**
	6 months	68	0.48 [0.21–0.63]	0.56 [0.39–0.69]	<0.001***	7	0.74 [0.62–0.77]	0.84 [0.58–0.84]	0.240
EQ-5D-5L Mobility	1 month	250	3.00 [2.00–4.00]	3.00 [2.00–3.00]	0.003**	23	2.00 [1.00–3.00]	2.00 [1.00–2.50]	0.058
	3 months	135	3.00 [2.00–4.00]	3.00 [2.00–3.00]	0.076	17	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.240
	6 months	68	3.00 [2.00–4.00]	3.00 [2.00–4.00]	0.400	7	2.00 [1.50–2.50]	1.00 [1.00–2.00]	0.110
EQ-5D-5L Selfcare	1 month	250	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.250	23	1.00 [1.00–2.50]	1.00 [1.00–2.00]	0.370
	3 months	135	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.360	17	1.00 [1.00–3.00]	2.00 [1.00–3.00]	0.400
	6 months	68	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.400	7	1.00 [1.00–1.50]	1.00 [1.00–2.00]	0.240
EQ-5D-5L Usual activities	1 month	250	3.00 [2.00–4.00]	3.00 [2.00–3.00]	<0.001***	23	2.00 [1.00–3.00]	2.00 [1.00–2.00]	0.032*
	3 months	135	3.00 [2.00–4.00]	3.00 [2.00–3.00]	0.005**	17	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.220
	6 months	68	3.00 [2.00–4.00]	2.00 [2.00–3.00]	0.038*	7	2.00 [1.00–2.00]	1.00 [1.00–2.00]	0.400
EQ-5D-5L Pain and Discomfort	1 month	250	4.00 [3.00–4.00]	3.00 [3.00–4.00]	<0.001***	23	4.00 [3.00–4.00]	2.00 [2.00–3.00]	<0.001***
	3 months	135	4.00 [3.00–4.00]	3.00 [2.50–4.00]	<0.001***	17	3.00 [3.00–4.00]	2.00 [2.00–3.00]	0.037*
	6 months	68	4.00 [3.00–4.00]	3.00 [3.00–4.00]	0.011*	7	3.00 [2.00–3.00]	2.00 [2.00–2.00]	0.075
EQ-5D-5L Anxiety and Depression	1 month	250	2.00 [1.00–3.00]	2.00 [1.00–3.00]	<0.001***	23	2.00 [1.00–2.50]	2.00 [1.00–2.00]	0.200
	3 months	135	2.00 [1.00–3.00]	2.00 [1.00–3.00]	<0.001***	17	2.00 [1.00–3.00]	1.00 [1.00–3.00]	0.260
	6 months	68	2.00 [1.00–3.00]	2.00 [1.00–3.00]	0.370	7	1.00 [1.00–2.00]	1.00 [1.00–2.50]	0.240
PGIC	1 month	239	N/A	5.00 [3.00–6.00]	N/A	23	N/A	6.00 [5.00–6.00]	N/A
	3 months	120	N/A	5.00 [4.00–6.00]	N/A	17	N/A	6.00 [5.00–6.00]	N/A
	6 months	57	N/A	5.00 [5.00–6.00]	N/A	7	N/A	7.00 [6.50–7.00]	N/A

Median and interquartile ranges (IQR) are shown. SQS = Single-Item Sleep Quality Scale, GAD-7 = Generalized Anxiety Disorder-7, PGIC = Patient Global Impression of Change. For GAD-7, a lower score indicates reduced anxiety. For SQS,©PGIC, and EQ-5D-5 L, higher scores indicate improvement. *p < 0.050, ** p < 0.010, *** p < 0.001.

Table 5. Multivariate analysis of factors increasing the risk of adverse events from cannabis-based medicinal products.

Variable	Odds Ratio [95% Confidence Interval]	P-value
Age
18–30	-	Ref
31–40	0.757 [0.386–1.485]	0.418
41–50	0.780 [0.407–1.495]	0.455
51–60	1.198 [0.625–2.300]	0.586
61–70	1.071 [0.520–2.206]	0.852
71–80	1.536 [0.683–3.453]	0.300
81+	1.485 [0.502–4.388]	0.475
Cannabis status
Current users	-	Ref
Ex-users	2.286 [1.246–4.195]	0.008**
Naïve	2.515 [1.470–4.301]	<0.001***
Gender
Female	-	Ref
Male	0.403 [0.262–0.618]	<0.001***
Treatment type
Oils	-	Ref
Oils and dried flower	1.005 [0.639–1.581]	0.984

A multivariate binary logistic regression model was used to assess the effect of age, cannabis status, gender, and treatment type on the chances of experiencing adverse events by calculating odds ratios and 95% confidence intervals. Naïve users had never used cannabis before, ex-users had previously used cannabis but were not using it at the time of starting their prescription. Current users were using non-prescription cannabis up until the time of their prescription. Ref = reference group. *p < 0.050, **p < 0.010, ***p < 0.001.