electrical stimulation therapy in the treatment of cigarette smoking

ELECTRICAL STIMULATIONTHERAPY IN THE TREATMENT OF

CIGARETTE SMOKING

A.J. GEORGIOU*C.P. SPENCER

University of Sheffield, Sheffield, UK

G.K. DAVIESNorthern General Hospital, Sheffield, UK

J. STAMPRoyal Hallamshire Hospital, Sheffield, UK

ABSTRACT: In this study electrical stimulation therapy (EST) is explored as a

possible new treatment for smoking cessation within a randomized controlled trial. The

investigation follows reports of several authors that electrical stimulation applied to

specific acupuncture points is effective in treating a variety of drug dependencies,

including cigarette smoking. Three key features of treatment (electrical stimulation,

frequency modulation, and electrode placement), were investigated in a 2 � 2 � 2

factorial design, resulting in eight treatment combinations. Out of 265 smokers

recruited into the trial 216 completed the one-week treatment. Outcome was assessed

in terms of complete abstinence from smoking and symptomatic relief of withdrawal

symptoms. Smokers receiving active electrical stimulation obtained higher abstinence

rates than those in the inactive groups although the difference did not achieve

statistical significance (all active vs. all placebo groups: �1,12 = 0.50, p > 0.10, 95%

confidence interval = ÿ 8.04 to + 17.44%; most effective vs. least effective group:

�1,12 = 3.11, p = 0.08, CI0.95 = ÿ 2.2 to + 48.8%). The efficacy of electrical stimulation

therapy for smoking is not supported.

*Direct all correspondence to: A. Georgiou, Division of Public Health, Nuffield Institute for Health, University of

Leeds, Leeds, LS2 9PL UK; E-mail: [email protected]

JOURNAL OF SUBSTANCE ABUSE, Volume 10, Number 3, pages 265± 274.

Copyright # 1999 by Elsevier Science Inc.

All rights of reproduction in any form reserved.

ISSN: 0899-3289

INTRODUCTION

Alternative treatments such as homeopathy, hypnosis, and acupuncture are becoming

increasingly popular among those wishing to stop smoking. A series of reports suggest

electro-acupuncture and other forms of electrical stimulation as effective means of

detoxifying from addictive drugs, including alcohol and cigarettes (e.g., Wen and Cheung,

1973; Sainsbury, 1974; Man and Chuang, 1980; Patterson, 1986). Wilkinson (1987)

reports smoking abstinence rates as high as 65% for a technique named transcranial

electrotherapy technology (TCET), in which small electrical currents are applied to the ear

lobes for a week, compared with an abstinence rate of 25% in the control group.

An alternative treatment that has attracted considerable interest is NeuroElectric

Therapy (NET; Patterson, 1976, 1986), a mild form of electrical stimulation administered

transcutaneously to the ear. Ten days continuous use of NET is claimed to reduce

substantially withdrawal experience for a variety of drugs, including alcohol and cigarettes

(Patterson, 1986). A more recent study by Gariti et al. (1992), however, indicates that NET

is no more effective in attaining drug abstinence or reducing the symptoms of withdrawal

than placebo NET.

The specific mechanism by which acupuncture and electrical stimulation achieve their

effects is unknown. Several theories have been suggested such as the gate-control theory

(Melzack and Wall, 1965); neurochemical release of various neurotransmitters (e.g.,

Clement-Jones et al., 1980; Salar et al., 1981); diffuse noxious inhibitory control (LeBars

et al., 1980), where stimulation of one body surface suppresses pain in another; and the

induction of a strong placebo response (Petrie and Hazleman, 1985).

Electrical stimulation is becoming increasingly popular with several different treatment

schedules currently in operation. Despite this, little is known about its efficacy in treating

drug dependence (Whitehead, 1978) and no definitive clinical evaluation of the best

stimulation parameters for attaining analgesia has been achieved (Leo et al., 1986). NET

appears to be one of the most popular methods used for drug dependence although an

adequately controlled study of this technique for smoking cessation has not been

conducted to date.

This study reports a randomized controlled trial designed to assess the potential value

of electrical stimulation therapy (EST) as a means of achieving abstinence from smoking

and reducing withdrawal symptoms. Because patenting of NET stimulation prevented

independent evaluation of its effectiveness, conventional transcutaneous electrical nerve

stimulation (TENS) was employed. This investigation incorporated the most salient

features of the Pharmakon±Patterson and other types of electrical stimulation therapy

currently in use for smoking cessation (Georgiou, 1995). These features are: (a) active

electrical stimulation, (b) modulation, and (c) electrode placement.

METHODS

Subjects

Ethical approval was obtained for the study and all participants gave informed consent

to participate. Those eligible were aged over 18 years and smoked ten cigarettes/day or

more for the last year. Exclusion criteria were history of serious organic illness, pregnancy,

JOURNAL OF SUBSTANCE ABUSE Vol. 10/No. 3/1998266

use of a cardiac pacemaker, and co-intervention for smoking. Two hundred sixty-five

smokers (107 males, 158 females) were recruited, consisting of a general public sample

(79%) responding to local publicity of the trial, and two smaller samples of psychiatric

nursing staff (14%) and local government employees (7%) recruited at their workplace.

The general public sample received treatment demonstrations at Sheffield University

Psychology Department; the two other samples at work. Following this, treatment was

self-administered at home or work.

Procedures

The trial was conducted in two phases: Phase 1 was designed to obtain a preliminary

indication of treatment effectiveness and establish the feasibility of running a larger scale

trial. Phase 2 immediately followed Phase 1, the procedure being identical, except for an

extension of the 3-month follow-up to 6- and 12-months.

Three stimulation parameters were investigated in a 2 � 2 � 2 factorial design,

comprising the following factors:

ACTIVE STIMULATION

A frequency of 5 or 10 Hz for 5 days is recommended for smoking cessation (Patterson,

1986; Kusumi, 1987). Active stimulation was produced by two portable, battery powered

stimulators: Tenzcare Model 6880 (3M Healthcare, Loughborough, UK) and Microtens

Model 7737 (Neen Pain Management Systems, Middlesex, UK). Both devices meet

serviceability requirements and comply with electrical safety and performance standards

(Stamp and Rose, 1984). Stimulation parameters were preset by the manufacturers (0.150

msec pulse width; rectangular wave direct current pulse shape; asymmetric, biphasic

modified square output waveform; 0.50 mA/0.80 mA into 1 K load amplitude). Identical

placebo machines had their output disconnected from the electrodes.

MODULATION

To avoid nerve adaptation and maintain stimulus perception at a comfortable level,

periodic readjustment of pulse frequency or duration is required (modulation). The

two electrical stimulators differed in this respect, one producing a continuous fre-

quency of 10 Hz (Microtens), the other a modulated frequency between 7 and 14 Hz

(Tenzcare). Evidence suggests that a frequency of 10 Hz may stimulate b-endorphin

release (Clement-Jones et al., 1980; Salar et al., 1981) and acetylcholine (Youjing et al.,

1985), whereas a frequency of 15 Hz is thought to activate a mixture of b-endorphin,

enkephalins, and dynorphins (Han et al., 1984). Tampering of stimulation parameters was

prevented by having them preset internally by the manufacturer (Microtens) or conceal-

ment of controls under an integral cover sealed with an adhesive label (Tenzcare).

ELECTRODE PLACEMENT

The electrode placement site used to treat drug dependence is described as being in the

mastoid process behind the ear (e.g., Gomez and Mikhail, 1978; Patterson, 1986),

covering points SJ18 (Quimai) and SJ17 (Yifeng) on traditional acupuncture charts.

Subjects in the control condition had electrodes placed on an alternative acupuncture point

located on the upper back (point SI15: Jianzhongshu). There is no previous evidence of the

Electrical Stimulation Therapy and Smoking 267

effectiveness of this point for smoking withdrawal. Disposable, pre-gelled, self-adhesive

electrodes were used throughout the study.

Participants gave their informed consent to participate in the study. Treatment

commenced one week following an initial interview where baseline measurements were

taken. All procedures were standardized as far as possible. Participants were allocated,

according to a table of random numbers, to receive active or inactive treatment within one

of the eight treatment groups (see Table 1). Treatment was administered by a single

clinician blinded as to whether the treatment was active or inactive. Coding and regular

servicing of the TENS units was conducted independently by a medical physicist who had

no contact with the subjects at any time.

The treatment schedule consisted of an initial 30-min stimulation period followed by

15±30 min stimulation (maximum 1 h) each time withdrawal symptoms or craving were

experienced. Participants were advised to take rest periods of at least 20 min between

stimulation periods. Electrodes were left in situ throughout the day to enable immediate

activation and removed when driving, bathing, or sleeping. Stimulators were loaned for 7

days use at home or work. An instruction manual was provided in addition to general

preparatory advice and standard self-help booklets.

Measures

Several measures were administered at baseline, including the following.

ADDICTION RESEARCH UNIT (ARU) SMOKING QUESTIONNAIRE

A self-report measure devised by researchers at the Institute of Psychiatry, London, to

obtain information on participants' smoking history, behavior and attitudes.

END-EXPIRED AIR CARBON MONOXIDE (CO)

It was measured at baseline, pretreatment and posttreatment using an EC50 Smoker-

lyser (Bedfont Technical Instruments, Kent, UK), providing a valid biochemical means of

abstinence verification (Jarvis et al., 1986).

VISUAL ANALOGUE SCALES (VAS) OF WITHDRAWAL SYMPTOMS

Self-reports of perceived severity of sixteen withdrawal symptoms associated with

cigarette abstinence (Shiffman, 1979; West et al., 1987), including craving, irritability,

feeling hungry, light-headedness, anxiety, etc., were recorded on standard 10 cm visual

analogue scales (VAS). Scores were converted to 10-point scales, higher scores indicating

TABLE 1Proportion of Subjects Abstaining in Each Treatment Group

Active Treatment Group Inactive Treatment Group

1 M/E 2 M/B 3 C/E 4 C/B 5 M/E 6 M/B 7 C/E 8 C/B

Group size 24 30 24 30 24 30 24 30

% Abstainers 50.0 40.0 29.2 33.3 41.7 36.7 29.2 26.7

Note. M = modulated, C = continuous, E = ear electrode placement, B = back electrode placement.


greater symptom severity. This method provides valid and reliable measurements (Aitken,

1969; Price et al., 1983).

THE FAGERSTROÈ M TOLERANCE QUESTIONNAIRE

This is a questionnaire of demonstrated validity (FagerstroÈm and Schneider, 1989),

containing eight questions about smoking habits (scoring range 0±11) providing an

indirect indication of physical dependence on nicotine.

FOLLOW-UP

Self-report questionnaires were completed at 24 h and 7 days after treatment initiation.

Postal follow-ups were conducted at 1- and 3-months posttreatment termination for Phase

1 subjects, and 1-, 6-, and 12-months posttreatment termination for Phase 2.

The primary outcome variable was defined as smoking less than one cigarette/day

during the treatment period and complete abstinence for at least three days prior to

the posttreatment follow-up, verified by a CO reading of 10 parts per million (ppm) or less.

Analysis

Data analysis was conducted using SPSS version 4.0 (SPSS, 1990). Non-parametric,

two-tailed tests were employed where data was non-normally distributed. As this was the

first formal controlled trial of electrical stimulation for smoking cessation, up to three

interim analyses were planned to monitor the main primary outcome variable, complete

abstinence. Interim analyses conducted at the end of Phase 1 and Phase 2 indicated no

difference in the overall abstinence rate or in the range of abstinence rates across

individual treatment groups. Because the likelihood of obtaining a clinically and

statistically significant difference between any of the treatment groups was remote, even

with a much larger sample size, the trial was terminated at this stage.

RESULTS

Sample

No differences were observed on pretreatment variables or ability to abstain between

those administered treatment at different sites or between Phase 1 and Phase 2 subjects.

Therefore, all groups were combined for main analyses.

Participants (mean age = 43.3 years, SD = 12.08, range 20±73) smoked an average

of 24 cigarettes/day (SD = 8.27, range 10±60), had smoked for a mean of 26.6 years

(SD = 12.08), and had an average FagerstroÈm score of 6.69 (SD = 1.92), indicating

a moderate level of physical dependence. Mean carbon monoxide levels for the

sample were 30 ppm at baseline, 24 ppm immediately prior to treatment, and 12.5 ppm

at posttreatment.

End-of-treatment Abstinence Rates

Of the 265 subjects receiving treatment, seven were withdrawn following skin reactions

from electrode adhesive, eight were excluded because of an electrical fault on one


stimulator, and 34 did not complete the prescribed 7-day treatment. Attrition rates did not

differ significantly across treatment conditions (�1,72 = 3.15, p > 0.10).

The overall abstinence rate on an intention-to-treat basis was 29% (35.6% for the 216

smokers completing treatment). Of those completing treatment, the number abstaining in

each treatment group ranged from 50% in group 1 to 26.7% in group 8 (Table 1) with no

significant main or interaction effects (�1,72 = 4.78, p > 0.10).

All active vs. all placebo groups proved equally effective (�1,12 = 0.50, p > 0.10; 95%

confidence interval (CI0.95) = ÿ8.04 to +17.44%) and the difference between the most

and least effective treatment groups (i.e., groups 1 and 8) also did not achieve

significance (�1,12 = 3.11, p = 0.08; CI0.95 = ÿ2.2 to + 48.8%). Fig. 1 illustrates

abstinence rates for each group receiving active electrical stimulation against the most

appropriate placebo group.

Analysis of pretreatment variables indicated that it was the less dependent smokers, as

indicated by cigarette consumption, FagerstroÈm, and baseline CO scores who experienced

greater ease in quitting smoking ( p < 0.05).

Long-term Abstinence and Relapse

Response rates for follow-up were 66% at 1 month (all samples); 36% at 3 months

(Phase 1 only); 70% at 6 months; and 67% at 12 months (Phase 2 only). Those not

FIGURE 1Percentage Success Rate Active vs. Inactive Groups. Mod/Ear: Active 50, Inactive 41.7;

Mod/Back: Active 40, Inactive 36.7; Cont /Ear: Active 29.2, Inactive 29.2;Cont/Back: Active 33.3; Inactive 26.7


responding were conservatively classified as smoking, regardless of actual smoking status.

Analysis of the main characteristics of responders and nonresponders for each period

separately, indicated no pretreatment differences on main smoking variables. Overall

sustained abstinence rates for those responding to follow-up were 19, 14, 11 and 9% for 1,

3, 6 and 12 months, respectively for the combined sample. Abstinence rates between Phase

1 and Phase 2 samples did not differ significantly. Approximately three-quarters of those

not smoking at the end of treatment were estimated to have relapsed within the year

because only 26% of the Phase 2 sample sustained abstinence for a year.

Experience of Withdrawal Symptoms and Craving

Kruskal±Wallis (one-way ANOVA) tests revealed no significant differences between

treatment groups on self-reported visual analogue scale assessments of individual with-

drawal symptoms at baseline, 24 h, or 7 days ( p > 0.1). More direct questions from the

follow-up questionnaire, however, indicated that two-thirds of the sample felt the treatment

had been an important factor in reducing withdrawal experience and in their attempt to

stop smoking.

The three most commonly reported worst withdrawal symptoms at the end of

treatment, in order were irritability (n = 43), feeling disorientated / light-headed (n =

11), and headaches (n = 9). Irritability continued to be the most frequently cited worst

withdrawal symptom throughout follow-up while the frequency of other troublesome

symptoms varied widely. The most commonly reported situations for craving at 24 h

and end of treatment, in decreasing order of importance, were after a meal, first thing

in the morning, stressful and social situations. Generally, cravings diminished through-

out follow-up. From three months onwards, stressful situations became the most

powerful elicitor of cravings.

DISCUSSION

In terms of both abstinence and withdrawal experience, there was no evidence for

differential effectiveness on any of the three factors studied or of their interactions at

the end of treatment. It should be noted that the analyses reported are based largely on

treatment completion rather than the conventional intention-to-treat and are therefore less

conservative in terms of overall abstinence. This was considered clinically appropriate

because similar attrition rates were observed across treatment groups and the main

comparisons involved factors dependent on treatment administration. Self-report diaries

of treatment use indicated that participants had complied with the prescribed treatment

schedule although there was no objective verification of this fact. Limited follow-up data

prevented detailed assessment of long-term effects of treatment.

Out of the three treatment factors investigated, modulation contributed most to outcome

variance. Whether this was as a result of greater stimulation comfort, credibility, or more

sophisticated design of the modulated TENS device is not clear. It is interesting in this

regard that Langley et al. (1983) have observed an enhancement of the therapeutic effect of

placebo TENS by the addition of a distracting oscilloscope. The absence of a difference

between the two electrode sites, however, suggests that the chosen sites were not optimal


for smoking or that specific point location is irrelevant. Although not previously used for

the purpose of smoking cessation, the upper back electrode placement is a valid

acupuncture point in its own right. Thus, generalized acupuncture effects cannot be ruled

out completely.

Various theories can be postulated for the absence of differential treatment effects.

Standardized stimulation parameters were employed in this study. It is possible that

treatment effects may be enhanced by the use of individualized, symptom-specific

electrical frequencies or electrode placements as specified by the Pharmakon±Patterson

and other electro-acupuncture treatments. A study of individualized NET for opiate and

cocaine dependence conducted by Gariti et al. (1992), however, confirms the findings

of this study. No difference was observed between groups treated with active NET (0.6

to 4.3 mA) or placebo NET (0.2 mA) in either total abstinence rate or in the reduction

of withdrawal symptoms and craving. A possible interpretation of the results of Gariti

and colleagues and the present investigation is that placebo or study effects are largely

in operation. Stopping smoking in the absence of specific treatment effects has

interesting implications for the treatment of smoking in general and serves to emphasize

the importance of psychological and social factors in achieving success. This coupled

with the fact that it was the less dependent smokers who were able to stop smoking

suggests that the treatment acted as an important source of remoralization and

encouragement to quit.

The abstinence definition used in the present study was less stringent than the usual

7-days abstinence. This was chosen in recognition of the fact that smoking is a process

rather than a single act and that a small number of participants, having stopped initially,

might relapse within the first day yet recover from this and maintain abstinence for the

remainder of the treatment period. More than three-quarters of the sample were abstinent

for the complete treatment period. Interestingly, subjects who reported a brief lapse in the

early stages of treatment claimed that the cigarette had tasted unpleasant at this point and

had reinforced their attempt to quit.

Finally, there may have been insufficient power to detect real but small differences

between treatment conditions. Sample size calculations were based on two group

comparisons of main factors (e.g., all active vs. all inactive groups). Interim results

indicated that a clinically relevant advantage (i.e., 20% in the short-term, 10% long-term)

was unlikely to emerge between any of the treatment groups. The largest difference was

observed between groups 1 and 8 yet this would be considered clinically irrelevant in the

absence of a difference among group 1 and its most appropriate control (group 5). The

results of the interim analyses suggested that such a difference was unlikely to emerge

even with a much larger sample size.

As this is the first formal controlled trial of electrical stimulation therapy for smoking

cessation, more definitive conclusions will have to await the implementation of a

large-scale, multicenter trial. Given the lack of statistically significant differences between

the variations in treatment employed in the current study, future evaluations should

consider comparing electrical stimulation with existing treatments for smoking cessation,

such as nicotine replacement therapies.

ACKNOWLEDGMENTS: This research was supported in part by British Heart Foundation Grant

#1970641 and #1880999. The authors would also like to thank participants of the study, Neen Pain


Management Systems and 3M Healthcare for loan of TENS devices, and Mike Robinson for helpful

comments on an earlier version of this manuscript.

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electrical stimulation therapy in the treatment of cigarette smoking

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