Effects of stimulus parameters on motor seizure duration in electroconvulsive therapy

Figures & data

Table 1 Stimulus parameters in the first session

Age (years)	Sex	Pulse width (ms)	Frequency (Hz)	Train duration (s)	Current (mA)
<30	Female	1.4	60	1	0.7
	Male	1.4	70	1	0.7
30–60	Female	1.4	70	1.25	0.75
	Male	1.4	80	1.25	0.75
>60	Female	1.4	80	1.5	0.75
	Male	1.4	90	1.5	0.75

Table 2 Characteristics of the sessions‡

Variables	Sessions with inadequate seizure durations (n=519)	Sessions with adequate seizure durations (n=1,349)	z score or χ^2 (df)	P-value
Age (mean ± SD) (years)	48.18±17.51	39.48±16.43	−9.57	<0.001
<30 (%)	21.0	37.4	104.28 (2)	<0.001
30–60 (%)	44.9	48.1
>60 (%)	34.1	14.5
Male (%)	58.3	53.7	3.26 (1)	0.071
Number of courses (mean ± SD)	1.68±1.70	1.64±1.61	−0.02	0.984
Number of sessions (mean ± SD)	4.31±2.89	4.49±3.31	−0.525	0.600
Charge (mC) (mean ± SD)	359.85±220.86	274.3±160.4	−9.951	<0.001
Pulse width (ms) (mean ± SD)	1.4±0.07	1.41±0.05	−1.046	0.296
Frequency (Hz) (mean ± SD)	88.44±17.58	80.8±15.81	−8.855	<0.001
Train duration (s) (mean ± SD)	1.82±0.73	1.48±0.5	−10.659	<0.001
Current (mA) (mean ± SD)	770.27±50.76	763.96±51.27	−2.683	0.007
Use of benzodiazepine (%)	37.8	26.9	21.07 (1)	<0.001
Benzodiazepine dose‡‡ (mean ± SD)	1.39±1.13	1.17±0.86	−2.352	0.02
0 (%)	62.2	73.1	26.09 (2)	<0.001
≤1 (%)	21.4	18.2
>1 (%)	16.4	8.7
Use of antipsychotics (%)	14.3	11.7	2.23 (1)	0.135
Use of aripiprazole (%)	10.2	8.0	2.32 (1)	0.128
Use of olanzapine (%)	37.4	37.9	0.04 (1)	0.842
Use of quetiapine (%)	38.7	35.1	2.18 (1)	0.140
Use of clozapine (%)	13.7	18.0	5.03 (1)	0.025
Clozapine dose (mean ± SD)	240.32±142.31	268.0±146.26	−1.419	0.16
0 (%)	86.3	82.0	7.75 (2)	0.021
>200 (%)	5.2	4.9
≥200 (%)	8.5	13.1
Use of mood stabilizers (%)	11.0	6.6	10.00 (1)	0.002
Use of lithium (%)	1.9	1.5	0.11 (1)	0.744
Use of lamotrigine (%)	9.1	3.8	20.98 (1)	<0.001
Use of antidepressants (%)	6.1	48.7	21.59 (1)	<0.001

Notes:

‡ Analyzed by Mann–Whitney test or chi-square test.

‡‡ Calculated as the lorazepam equivalent dose; the difference in the mean dose of benzodiazepine was analyzed using the Mann–Whitney test; and the differences among the three groups (0, <1 mg/day, and >1 mg/day) were analyzed by the chi-square test.

Abbreviations: df, degree of freedom; SD, standard deviation.

Table 3 Odds ratios for associating demographics, psychotropic medications, and stimulus parameters with the occurrence of adequate seizure*

Variables	Crude OR (95% CI)	P-value	Adjusted† OR (95% CI)	P-value
Stimulus parameters#
Charge (mC)	0.998 (0.998–0.999)	<0.001	0.999 (0.998–1.000)	0.005
Pulse width (ms)	0.914 (0.502–1.665)	0.769	1.096 (0.620–1.940)	0.752
Frequency (Hz)	0.985 (0.975–0.994)	0.001	0.993 (0.983–1.004)	0.217
Train duration (s)	0.557 (0.441–0.705)	<0.001	0.632 (0.490–0.817)	<0.001
Current (mA)	1.031 (0.753–1.413)	0.847	1.283 (0.912–1.805)	0.153
Age (years)	0.972 (0.963–0.982)	<0.001
<30	1	<0.001
30–60	0.601 (0.406–0.890)	0.011
>60	0.250 (0.159–0.394)	<0.001
Sex	1.126 (0.789–1.608)	0.512
Number of courses	0.932 (0.847–1.025)	0.145
Number of sessions	0.987 (0.945–1.030)	0.544
Use of benzodiazepine	0.679 (0.535–0.861)	0.001
Benzodiazepine dose
None	1	0.004
≤1	0.759 (0.579–0.995)	0.046
>1	0.527 (0.373–0.745)	<0.001
Use of antipsychotics	1.113 (0.764–1.621)	0.576
Use of aripiprazole	0.665 (0.395–1.118)	0.123
Use of clozapine	1.189 (0.760–1.861)	0.448
Use of olanzapine	1.129 (0.818–1.559)	0.459
Use of quetiapine	0.846 (0.614–1.164)	0.304
Use of mood stabilizers	0.404 (0.226–0.721)	0.002
Use of lamotrigine	0.239 (0.125–0.459)	<0.001
Use of lithium	0.682 (0.220–2.109)	0.506
Use of antidepressants	0.799 (0.595–1.073)	0.136

Notes:

* Evaluated with logistic regression using a generalized estimating equation that accounted for clustering of observations in the same patient.

† Adjusted for age, benzodiazepine dose, and lamotrigine use.

# Frequency and train duration were considered as continuous variables; pulse width was dichotomized by 1.5 ms; and current was dichotomized by 800 mA.

Abbreviations: CI, confidence interval; OR, odds ratio.

Table 4 Odds ratios for associating stimulus parameters with the occurrence of adequate seizure in age-dependent subgroups*

Stimulus parameters#	Crude OR (95% CI)			Adjusted† OR (95% CI)
	Age <30 (N=614)	Age 30–60 (N=882)	Age >60 (N=372)	Age <30 (N=614)	Age 30–60 (N=882)	Age >60 (N=372)
Charge (mC)	1.000 (0.997–1.002)	0.999 (0.998–1.000)§	0.999 (0.998–1.000)§	1.001 (0.997–1.005)	0.999 (0.997–1.000)§	0.999 (0.997–1.008)§
Pulse width (ms)	Infinite	1.152 (0.471–2.814)	0.789 (0.375–1.663)	–	1.206 (0.524–2.777)	0.785 (0.358–1.721)
Frequency (Hz)	1.003 (0.976–1.031)	0.991 (0.976–1.006)	0.992 (0.997–1.008)	1.010 (0.978–1.044)	0.991 (0.976–1.007)	0.991 (0.975–1.007)
Train duration (s)	0.674 (0.375–1.212)	0.524 (0.356–0.773)§	0.765 (0.540–1.084)	0.814 (0.364–1.819)	0.521 (0.351–0.773)§	0.755 (0.532–1.072)
Current (mA)	0.900 (0.514–1.574)	1.347 (0.851–2.134)	1.522 (0.645–3.588)	1.179 (0.668–2.083)	1.257 (0.779–2.027)	1.548 (0.650–3.686)

Notes:

* Evaluated with logistic regression using a generalized estimating equation that accounted for clustering of observations in the same patient.

† Adjusted for benzodiazepine dose and lamotrigine use.

# Frequency and train duration were considered as continuous variables; pulse width was dichotomized by 1.5 ms; and current was dichotomized by 800 mA.

§ P<0.05.

Abbreviations: CI, confidence interval; OR, odds ratio.