Risk Factors for Tremor in a Population of Patients with Severe Mental Illness: An 18-year Prospective Study in a Geographically Representative Sample (The Curacao Extrapyramidal Syndromes Study XI)

Charlotte L. Mentzel; P. Roberto Bakker; Jim van Os; Marjan Drukker; Michiel R. H. van den Oever; Glenn E. Matroos; Hans W. Hoek; Marina AJ Tijssen; Peter N. van Harten

doi:10.5334/tohm.336

Figures & Tables

Table 1

Demographic Characteristics, Movement Disorder Prevalence, and Medication Use at Baseline

	No Tremor		Resting Tremor¹		Action Tremor¹		All Patients
	N	%^*	N	%^*	N	%^*	N	%^*
Demographic variables
Subjects	137	85	22	14	6	4%	162	100%
Age, mean SD	50.12	16.77	50.17	13.48	58.28	19.45	50.43	16.45
Male sex	94	69%	20	91%	5	83%	116	72%
Cocaine use	23	17%	5	23%	1	17%	28	17%
Diagnosis schizophrenia	112	82%	17	77%	3	50%	130	80%
Movement disorders
Dyskinesia	19	14%	3	14%	1	17%	22	14%
AIMS mean SD	6	4.11	6	4.58	2		6	4.06
Akathisia	5	11%	1	5%	0	0%	16	10%
BARS mean SD	2.53	0.74	4				2.63	0.81
Bradykinesia	32	23%	9	41%	4	67%	42	26%
UPDRS² mean SD	14.81	6.71	15.22	8.89	19	7.53%	14.93	7.03
Rigidity	22	16%	7	32%	2	33%	29	18%
UPDRS³ mean SD	8.64	3	6.71	3.77	9.5	3.54%	8.17	3.24
Medication variables
Antipsychotic type
No AP	16	12%	0	0%	1	17%	17	10%
FGA only	115	84%	20	91%	4	67%	137	85%
SGA only	5	4%	2	9%	1	17%	7	4%
Both AP types	1	1%	0	0%	0	0%	1	1%
AP DDD mean SD	1.58	1.48	2.05	1.88	1.12	0.78	1.62	1.53
Depot use	81	59%	15	68%	3	50%	97	60%
Tremor-inducing medication use	37	27%	4	18%	2	33%	43	27%
Tremor-reducing medication use	3	2%	0	0%	0	0%	3	2%
Anticholinergic load	2.58	2.55	3.41	2.54	3.5	1.97	2.72	2.55
Benzodiazepine DDD	0.23	0.64	0.34	0.7	0.08	0.2	0.24	0.64

Abbreviations: AIMS, Abnormal Involuntary Movement Scale; AP, Antipsychotic; BARS, Barnes Akathisia Rating Scale; DDD, Defined Daily Dose; FGA, First-generation Antipsychotic; SGA, Second-generation Antipsychotic; UPDRS, Unified Parkinson’s Disease Rating Scale.

1 Patients can have both action and resting tremor.

2 List items bradykinesia.

3 List items rigidity.

* Numbers in percentages except when stated otherwise.

Table 2

Relationship between Covariates and Tremor Subtypes in Psychiatric Patients with Severe Mental Illness, 18-year Follow-up Data

	Any Tremor			Resting Tremor			Action Tremor
	OR	95% CI		OR	95% CI		OR	95% CI
Demographic variables
Age	1.06^**	1.02	1.10	1.07^**	1.03	1.11	1.05	1.00	1.11
Sex	0.18^*	0.05	0.69	0.19^*	0.05	0.78	0.18	0.032	1.07
Cocaine use	8.32^**	2.01	34.4	10.53^**	2.22	49.94	14.04^**	2.38	82.96
Diagnosis	2.42	0.66	8.87	2.17	0.53	8.90	2.26	0.49	10.35
Other movement disorders
Dyskinesia	0.92^*	0.86	0.99	0.90^**	0.83	0.97	1.04	0.95	1.15
Akathisia	1.32	0.88	1.98	1.30	0.84	2.01	1.34	0.74	2.44
Bradykinesia	1.14^***	1.08	1.21	1.16^***	1.09	1.22	1.07^*	1.01	1.15
Rigidity	1.09	0.99	1.21	1.09	0.98	1.22	1.10	0.96	1.27
Medication variables
Benzodiazepine DDD	1.18	0.77	1.81	1.14	0.70	1.84	1.37	0.78	2.38
No antipsychotic use (base = only FGA)	0.57	0.13	2.51	0.54	0.11	2.57	1.75	0.27	11.51
Only SGA use (base = only FGA)	0.42	0.11	1.56	0.51	0.13	2.01	1.00	0.17	5.76
Both FGA and SGA (base = only FGA)	0.48	0.11	2.08	0.47	0.10	2.42	0.69	0.09	5.23
Antipsychotic DDD	1.12	0.84	1.48	1.13	0.84	1.53	0.97	0.66	1.45
Depot use (base= no)	2.15	0.90	5.17	2.14	0.85	5.40	1.65	0.47	5.81
Number of tremor inducing medications	2.23^*	1.10	4.52	1.83	0.86	3.92	4.54^***	1.90	10.86
Number of tremor reducing medications	0.71	0.09	5.76	0.45	0.05	4.21	5.94	0.63	55.94
Anticholinergic load	0.99	0.85	1.16	0.97	0.82	1.15	1.15	0.93	1.42

Abbreviations: CI, 95% Confidence Interval; DDD, Defined Daily Dose; OR, Odds Ratio; FGA, First-generation Antipsychotic; SGA, Second-generation Antipsychotic.

* p<0.05;

** p<0.01;

*** p<0.001.

Table 3

Time-lagged Relationship between Covariates and Tremor Subtypes in Psychiatric Patients with Severe Mental Illness, 18-year Follow-up Data

	All Tremor			Rest Tremor			Action Tremor
	OR	95% CI		OR	95% CI		OR	95% CI
Having tremor at the previous time point	7.87^***	3.45	17.94	9.86^***	3.80	25.63	0.24	0.03	1.96
Severity of tremor	1.20^***	1.08	1.34	1.22^**	1.05	1.41	2.62^***	1.64	4.18
Medication variables
Change in benzodiazepine dose	0.90	0.68	1.28	0.72	0.48	1.08	1.59	0.91	2.79
Change in antipsychotic dose	0.88	0.67	1.14	0.91	0.69	1.20	0.98	0.68	1.43
Switching antipsychotics	0.84	0.38	1.89	0.70	0.29	1.68	0.79	0.21	2.98
Getting depot medication	0.29^*	0.09	0.94	0.33	0.10	1.09	0.89	0.14	5.52
Stopping depot medication	1.97	0.60	6.50	2.04	0.60	6.94	1.90	0.29	12.32
Number of tremor inducing medications	0.56	0.30	1.06	0.67	0.34	1.34	0.45	0.17	1.18
Number of tremor reducing medications	0.27	0.04	1.71	0.63	0.11	3.72	0.08^*	0.01	0.55
Anticholinergic load	1.19^*	1.04	1.37	1.24^**	1.08	1.43	1.10	0.88	1.38