A block randomized controlled trial of a brief smoking cessation counselling and advice through short message service on participants who joined the Quit to Win Contest in Hong Kong

Abstract

The present trial examined the effectiveness of brief interventions for smokers who joined the Hong Kong Quit to Win Contest to quit smoking. A block randomized controlled trial allocated 1003 adult daily smokers to three groups: (i) The TEL group (n = 338) received a 5-min nurse-led telephone counselling; (ii) The SMS group (n = 335) received eight text messages through mobile phone and (iii) The CONTROL group (n = 330) did not receive the above interventions. Participants with biochemically verified abstinence at 6-month follow-up could receive cash incentive. The primary outcome was the self-reported 7-day point prevalence (PP) of tobacco abstinence at 6-month follow-up. The abstinence rate in the TEL, SMS and CONTROL group was 22.2, 20.6 and 20.3%, respectively (P for TEL versus CONTROL = 0.32; P for SMS versus CONTROL = 0.40). When abstinence at 2-, 6- and 12-month follow-up was modelled simultaneously, the TEL group had a higher abstinence than the CONTROL group (Adjusted OR = 1.38, 95% CI = 1.01–1.88, P = 0 .04). In the Quit to Win Contest, the brief telephone counselling might have increased abstinence, but the text messages had no significant effect. Further studies on intensive intervention and interactive messaging services are warranted.

Introduction

Quitting smoking can reduce the risk of many tobacco-related diseases, with substantial gains in quality of life and life expectancy. In China, with one-third of the world’s smokers, over 75% of the smokers do not want to quit [1]. Only 8.2% of the quitters sought counselling services or used pharmaceutical therapy such as nicotine replacement therapy [2]. In Hong Kong, the most westernized and urbanized city in China and with the lowest smoking prevalence in the developed world, the proportion of hardcore smokers (defined as those who had no intention to quit, no quit attempt and consumed 15 or more cigarettes a day) increased from 21.8% in 2005 to 27.4% in 2008 [3], which was higher than several developed countries including the United States [4], Canada [5] and England [6] and was comparable to Norway and Italy [7, 8].

To attract more smokers to quit, Quit and Win contests have been organized to promote smoking cessation by using monetary and grand prizes as incentives. A systematic review, however, did not conclude about the effectiveness of such approach due to the lack of randomized controlled trials (RCTs) [9]. Three quasi-experimental studies found that the contests increased abstinence by at least 2-fold (Quit and Win group: 24%; Control group: 8%) compared with the nonparticipant control group [10–12], but a RCT did not find any significant difference between the Quit and Win group and the control group [13].

To increase abstinence, Quit and Win contests often provided additional interventions to assist participants to quit, including intensive counselling sessions (face-to-face, group or telephone) [12], short-term monetary incentives [12, 14–16] and printed educational materials [10, 11]. Providing brief interventions should be feasible for smokers recruited for Quit and Win contests, because the majority were in the contemplation or preparation stage of change [12, 13]. Also, they were more educated and had made more quit attempts than the general population of smokers [11, 12, 17]. Brief intervention is normally a short advice which lasts for 30 s to 10 min [18], or text messaging service via mobile phones [19]. Previous systematic reviews showed that brief advice by physicians [pooled risk ratio (RR) = 1.24, 95% CI 1.16–1.33] [18], counselling by nonphysician clinican (pooled odds ratio = 1.7, 95% CI 1.3–2.1) [20], telephone counselling (pooled RR = 1.37, 95% CI 1.26–1.50) [21] and text messages (pooled RR = 1.71, 95% CI 1.47–1.99) [19] were all effective and low-cost interventions to increase abstinence. As these strategies did not require much resource and professional training, they can be delivered to many smokers in a short period of time. No RCTs have tested if these interventions increase abtinence in the particpants in the Quit and Win contests.

The first Quit and Win Contest in Hong Kong, titled ‘Quit to Win Contest’, was organized by the Hong Kong Council on Smoking and Health (COSH) and the University of Hong Kong (Schools of Nursing and Public Health) in 2009. The Contest aimed to attract and encourage smokers to quit by rewarding them with financial incentives if they had acheived smoking abstinence at a predefined follow-up. In this Contest, we conducted a RCT on two additional brief interventions: (i) brief telephone counselling by a trained nurse (TEL group); (ii) Short Message Service (SMS) via mobile phone (SMS group), compared with no additional counselling or SMS (CONTROL group).

Methods

Trial design and participants

This was a single-blinded, parallel three-armed block RCT with each recruitment day as the unit of randomization (with allocation ratio of 1:1:1). The study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (IRB reference no.: UW09-236).

Eligible participants were (i) Hong Kong residents aged 18 or older; (ii) daily smokers who smoked at least one cigarette per day in the past 6 months; (iii) exhaled carbon monoxide (CO) of 4 ppm or above; (iv) able to communicate in Cantonese and read Chinese and (v) had a mobile phone to receive SMS. Smokers who were physically or mentally unable to communicate or currently following other forms of smoking cessation programme were excluded from this RCT.

The recruitment activities for the Quit to Win Contest took place at shopping malls or public areas in 16 out of the 18 districts in Hong Kong during May to July 2009. Participants who expressed an interest to join the Contest were screened for eligibility and tested on their exhaled CO to ascertain their smoking status. All eligible participants were asked to provide a written consent and complete a baseline questionnaire. Those eligible participants who were not willing to participate in the RCT could join the Contest and were assigned to the non-RCT group.

All participants were then given a eight-page self-help smoking cessation booklet, which was designed for the Contest by the organizing body (COSH) [22]. The recruitment staff advised the participants to start tobacco abstinence on or before 1 July 2009, or as soon as possible. After each recruitment activity, the participants were randomly assigned to one of the three trial arms (TEL, SMS or CONTROL group) by one of the authors and then received the intervention as stated in the protocol.

Participants who had biochemically validated abstinence at 6-month follow-up could enter into a lucky draw organized by COSH. Three winners of the lucky draw were each awarded HK$10 000 (US$1,282) cash incentive. Also, three prizes (each HK$3000 (US$385) cash incentive) were awarded to the nominators of the participants who had biochemically validated abstinence at 6-month follow-up.

Interventions

The TEL group received a 5-min telephone smoking cessation counselling by a trained nurse within seven days after enrolment. The brief ‘AWARD’ protocol was developed by the authors taking reference from the recommendations of the clinical practice guidelines in treating tobacco use and dependence [20] with substantial simplification and the use of the absolute risk of death from smoking [23]. The standard AWARD protocol included (i) ask the participants their smoking and quitting history (Ask), (ii) warn them about the serious health hazards of active and passive smoking, emphasizing ‘1 in 2 smokers will be killed by smoking induced diseases’ (Warn), (iii) advise them to quit smoking by emphasizing benefits and strategies of quitting (Advice), (iv) provide the contact information of publicly available smoking cessation services provided by the University of Hong Kong, Department of Health, Hong Kong or Hong Kong Hospital Authority (Refer) and (v) repeat the smoking cessation advice, encouragement and reminder at the 2-, 6- and 12-month follow-up (Do-it-again) (Supplementary Table SI). A standard check list was included in the intervention guide to ensure fidelity of the telephone counselling.

The SMS group received eight mobile telephone text messages which were constructed with reference to the eight-page smoking cessation booklet [22] (Supplementary Table SIII). As the participants might not read the booklet or pay less attention to too many messages they received via mobile phone daily, we delivered only eight messages in the intervention period. The content of the messages included (i) warning about the health hazards of smoking, (ii) benefits of quitting, (iii) contact information of publicly available smoking cessation services, (iv) strategies of quitting and (v) encouragement and reminder of follow-up. These messages had similar content with the AWARD protocol, but they had different design and form of delivery.

The CONTROL group and the non-RCT group did not receive any intervention above other than the self-help booklet and the contact information of the smoking cessation services at the enrolment.

Follow-up and outcome measures

Follow-up calls were made to all the participants at 2, 6 and 12 months after the enrolment with standardized questionnaires by trained interviewers who were blinded to the group assignment. At least seven call attempts at different times were made before participants were considered as loss to follow-up. Participants who reported no smoking in the past 7 days were considered as self-reported quitters. Self-reported quitters at 6 and 12 months were invited to participate in a biochemical validation including measurement of exhaled CO and salivary cotinine level by NicAlert strips (www.nymox.com). The criteria for validated abstinence were exhaled CO <4 ppm and salivary cotinine <10 ng/ml [24, 25].

The primary outcome was self-reported 7-day point prevalence (PP) tobacco abstinence at 6-month follow-up. The secondary outcomes included self-reported 7-day PP tobacco abstinence at 2- and 12-month follow-up, biochemically validated tobacco abstinence at 6- and 12-month, had at least one quit attempt lasting for at least 24 h (quit attempt rate), and reduction in daily cigarette consumption by at least 50% compared to baseline (reduction rate) at all follow-ups. Except the biochemically validated abstinence, all the outcomes were based on self-reporting.

Other measures

At baseline, demographic characteristics (e.g. age, gender, marital status, number of children, education level, employment status and monthly household income), smoking characteristics (e.g. daily cigarette consumption and Heaviness of Smoking Index) [26], any quit attempt in lifetime, intention to quit smoking and psychological characteristics of quitting (perceived importance, difficulty and confidence to quit; Scale 0–10, 0 lowest, 10 highest) were enquired.

Sample size

The sample size calculation was based on the primary outcome of the self-reported 7-day PP quit rate at the 6-month follow-up. A 2.5% level of significance was set in all analyses for multiple comparisons (TEL versus CONTROL group; SMS versus CONTROL group). Based on a previous study, the 7-month self-reported tobacco abstinence of smokers who joined a Quit and Win contest and received self-help booklet was 5% [13]. Assuming the quit rate in the CONTROL group is 5% and to detect a 5% percentage point difference (i.e. 10% in each of the intervention groups or an odds ratio of 2.11), we needed 300 subjects per group by a two-tailed chi-square test to achieve a power of 80% and a significance level of 2.5% to detect a difference in quit rate between the TEL and CONTROL group, and the SMS and CONTROL group. Adding 5% for attrition during follow up, the overall sample size of the study should be 948.

Randomization

Block randomization was used to allocate participants into the three RCT groups and to ensure that the size of the three groups were similar. Block randomization of each participant after enrolment was feasible as all the participants received the same onsite interventions before being randomized. To ensure that the size of the three groups was similar, one of the authors (DYPL) who did not participate in the subject recruitment generated random permutations of the three RCT arms within each block, using the web site http://www.random.org (a web site for generating random integers). Then, the investigator allocated the random permutations of treatments to the list of the participants, and then passed the list of subjects in the TEL group to the trained smoking cessation counsellors to deliver the telephone counselling, and the list of the SMS group to research assistants to send the SMS text messages. Recruitment staff were blinded from the allocation of participants.

Allocation concealment

The randomization and allocation were conducted by the author who did not participate in subject recruitment to ensure allocation concealment. To achieve balanced number of subjects in each arm, the allocation sequence was sequentially generated by the author based on block randomization (with each recruitment session as a block) using the web site http://www.random.org.

Blinding

The RCT was single-blinded that all recruitment staff and assessors were not aware of the group allocation at the follow-up assessment.

Statistical analysis

Data analysis was performed using the Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, USA) version 20.0 for Windows. We used the end-of-treatment approach to examine the outcomes at 2-, 6- and 12-month follow-ups separately [27]. Multivariate logistic regression was used to estimate odds ratios for the primary and secondary outcomes with adjustment for other variables. Also, considering the correlation of outcome within the same subject, a post hoc analysis by generalized estimating equation (GEE) models was used to summarize the effect of interventions at all follow-ups with the adjusted odds ratios [27]. The analysis adopted a longitudinal approach with an exchangeable structure for the correlation matrix of the outcome. All the 1003 subjects who consented and randomly allocated to the three RCT groups were included in the analysis by intention-to-treat analysis, i.e. all participants who were lost at follow-ups were assumed as current smokers. Twenty-eight participants in the TEL group did not receive the telephone counselling, and two participants in the SMS group did not receive all the text messages because they provided invalid telephone number or refused to receive the telephone call or SMS after enrolment. Sensitivity analyses was conducted to compare the outcomes between TEL and CONTROL group as well as the SMS and CONTROL group with the exclusion of these 30 participants. The mean scores of perceived importance, difficulty and confidence to quit for the three groups were analysed to assess how their motivation to quit was changed during the study period. Independent samples t-test was conducted to compare the mean scores in the three groups at all the follow-ups, and compare the mean score at 2-, 6- and 12-month with the baseline mean score within each RCT group.

Results

Participants’ enrolment

During 30 May to 15 July 2009, COSH set up 23 recruitment sessions (each from noon to 8 pm) and recruited 1119 smokers for the Quit to Win Contest. 108 (9.7%) did not meet the inclusion criteria, and 8 (0.7%) refused to participate. 1,003 (89.6%) were eligible and consented to participate in the RCT. They were randomly assigned to TEL (n = 338), SMS (n = 335) or CONTROL group (n = 330) (Fig. 1). All these participants were analysed for the primary and secondary outcomes.

Fig. 1.

CONSORT flow diagram of the RCT.

Intervention, study completion and loss to follow-up

Twenty-four of 338 (6.5%) participants in the TEL group provided invalid telephone contact number, and 4 of 338 (1.2%) refused to receive telephone intervention subsequently. In the 335 smokers in the SMS group, 333 (99.4%) received all the 8 SMS text messages and 2 refused to receive further text messages from us after receiving the first text message.

The retention rate for the TEL, SMS and CONTROL groups at 2-month follow-up was 70.1, 68.7 and 76.1%, respectively. At 6-month follow-up, 66.9% of the TEL group, 73.1% of the SMS group and 70.6% of the CONTROL group were successfully contacted for completing the questionnaire. At 12-month follow-up, 66% of the TEL group, 65.1% of the SMS group and 63.6% of the CONTROL group provided data. One participant in the TEL group died before the 12-month follow-up.

More participants in the TEL group were aged 40–59 years (TEL: 52.7%; CONROL: 49.1%; P = 0.04), single/divorced/widowed (TEL: 26.1%; CONTROL: 19.5%; P = 0.05) and employed (TEL: 57.3%; CONTROL: 48.3%; P = 0.02) than the CONTROL group. The SMS group had a higher proportion of single/divorced/widowed than the CONTROL group (SMS: 26.1%; CONTROL: 19.5%; P = 0.02). No significant difference in other demographic characteristics, smoking profile, level of nicotine dependency, quitting history and psychological characteristics of quitting in the three RCT groups were observed (Table I).

Table I.

Baseline characteristics of the participants

	TEL Group (n = 338)	SMS Group (n = 335)	CONTROL (n = 330)	P value
				TEL versus CONTROL	SMS versus CONTROL
Demographic characteristics
Male sex, n (%)	273 (80.8)	270 (80.6)	277 (83.9)	0.31	0.27
Age group, years, n (%)
18–39	130 (38.5)	131 (39.1)	118 (35.8)	0.04	0.64
40–59	178 (52.7)	153 (45.7)	162 (49.1)
60 or above	30 (8.9)	51 (15.2)	50 (15.2)
Education level, n (%)
Primary or below	73 (21.6)	72 (21.5)	72 (21.8)	0.40	0.42
Secondary	240 (71.0)	238 (71.0)	224 (67.9)
Post-secondary	25 (7.4)	25 (7.5)	34 (10.3)
Marital status, n (%)
Married/cohabitating	249 (73.9)	244 (72.8)	264 (80.5)	0.05	0.02
Single/divorced/widowed	88 (26.1)	91 (27.2)	64 (19.5)
Missing	1	0	2
Had children, n (%)	247 (73.1)	246 (73.4)	248 (75.2)	0.54	0.66
Employment status, n (%)
Employed	193 (57.3)	188 (56.3)	159 (48.3)	0.04	0.12
Self-employed	46 (13.6)	41 (12.3)	46 (14.0)
Unemployed/ retired/ housekeeper/student	98 (29.1)	105 (31.4)	124 (37.7)
Missing	1	1	1
Monthly household income in HK$, n (%)
< $10 000	113 (33.6)	147 (44.3)	129 (39.6)	0.25	0.28
$10 000–$19 999	140 (41.7)	121 (36.4)	119 (36.5)
≥ $20,000	83 (24.7)	64 (19.3)	78 (23.9)
Missing	2	3	4
Smoking profile
Daily cigarette consumption, n (%)
1–10	139 (41.1)	140 (42.2)	144 (44.0)	0.65	0.73
11–20	143 (42.3)	148 (44.6)	136 (41.6)
>20	56 (16.6)	44 (13.3)	47 (14.4)
Missing	0	3	3
Nicotine dependency (Heaviness of Smoking Index), n (%)
Heavy (HSIa: 4–6)	119 (35.2)	107 (32.2)	101 (31.0)	0.25	0.74
Light (HSIa: 0–3)	219 (64.8)	225 (67.8)	225 (69.0)
Missing	0	3	4
Had ever made a quit attempt before, n (%)	228 (67.5)	240 (71.6)	244 (73.9)	0.07	0.54
Intended to quit smoking, n (%)
Within the next 7 days	221 (65.6)	221 (66.2)	223 (67.6)	0.44	0.71
Within the next 30 days	76 (22.6)	71 (21.3)	62 (18.8)
Beyond the next 30 days/undecided	40 (11.9)	42 (12.6)	45 (13.6)
Missing	0	3	4
Perceived importance of quitting, mean (SD) (Scale 0–100)	7.80 (2.36)	7.82 (2.22)	7.98 (2.43)	0.33	0.37
Perceived difficulty of quitting, mean (SD) (Scale 0–100)	6.99 (2.91)	7.13 (2.82)	6.73 (3.12)	0.27	0.08
Perceived confidence of quitting, mean (SD) (Scale 0–100)	6.02 (2.60)	6.23 (2.60)	6.47 (2.65)	0.026	0.23

^aHSI, Heaviness of Smoking Index.

Primary and secondary outcomes

The self-reported 7-day PP abstinence for the three groups at 6-month follow-up was 22.2, 20.6 and 20.3%, respectively. The difference between TEL and CONTROL group (P = 0.32), and SMS and CONTROL group (P = 0.40) was statistically insignificant. Sixty-one of the 211 self-reported quitters, with 22 (29.3%) in the TEL group, 21 (30.4%) in the SMS group and 18 (26.9%) in the CONTROL group, participted in the biochemical validation. There was no significant difference in the validated quit rate in the three groups (Table II).

Table II.

Self-reported abstinence, biochemically validated abstinence, reduction in daily cigarette consumption by at least 50% (including quitters) and quit attempt (including quitters) at 2-, 6- and 12-month follow up^a

				Absolute difference in % point (95%CI)		Odds ratio (95%CI)
	TEL (n = 338)	SMS (n = 335)	CONTROL (n = 330)	TEL versus CONTROL	SMS versus CONTROL	TEL versus CONTROL	SMS versus CONTROL
Self-reported 7-day PP quit rate
2 months	78 (23.1)	66 (19.7)	76 (23.0)	0.05 (−6.34, 6.43)	3.33 (−2.90, 9.56)	1.00 (0.70, 1.43)	0.82 (0.57, 1.19)
6 months	75 (22.2)	69 (20.6)	67 (20.3)	1.89 (−4.32, 8.09)	0.29 (−5.84, 6.43)	1.12 (0.77, 1.62)	1.02 (0.70, 1.49)
12 months	66 (19.5)	60 (17.9)	60 (18.2)	1.34 (−4.59, 7.28)	0.27 (−5.57, 6.12)	1.09 (0.74, 1.61)	0.98 (0.66, 1.45)
Biochemically validated quit rate
6 months	17 (5.0)	16 (4.8)	18 (5.5)	0.42 (−2.96, 3.81)	0.68 (−2.67, 4.03)	0.92 (0.47, 1.82)	0.87 (0.44, 1.74)
12 months	16 (4.7)	10 (3.0)	17 (5.2)	0.42 (−2.87, 3.71)	2.17 (−0.84, 5.17)	0.91 (0.45, 1.83)	0.57 (0.26, 1.26)
Self-reported reduction in daily cigarette consumption ≥ 50%
2 months	151 (44.7)	134 (40.0)	146 (44.2)	0.43 (−7.11, 7.97)	4.24 (−3.26, 11.74)	1.02 (0.75, 1.38)	0.84 (0.62, 1.14)
6 months	132 (39.1)	138 (41.2)	121 (36.7)	2.39 (−4.97, 9.74)	4.53 (−2.88, 11.93)	1.11 (0.81, 1.52)	1.21 (0.89, 1.65)
12 months	110 (32.5)	104 (31.0)	97 (29.4)	3.15 (−3.86, 10.16)	1.65 (−5.33, 8.63)	1.16 (0.84, 1.61)	1.08 (0.78, 1.50)
Quit attempt(s) with smoking abstinence ≥ 24 h
2 months	137 (40.5)	130 (38.8)	152 (46.1)	5.53 (−1.98, 13.03)	7.25 (−0.24, 14.75)	0.80 (0.59, 1.09)	0.74 (0.54, 1.01)
6 months	149 (44.1)	168 (50.1)	158 (47.9)	3.80 (−3.76, 11.35)	2.27 (−5.33, 9.87)	0.86 (0.63, 1.17)	1.10 (0.81, 1.49)
12 months	129 (38.2)	135 (40.3)	133 (40.3)	2.14 (−5.27, 9.54)	0.00 (−7.45, 7.46)	0.91 (0.67, 1.24)	1.00 (0.73, 1.36)

^aBy intention-to-treat analysis: all participants who did not respond at follow-up were considered as current smokers, or did not made a quit attempt during the follow up period, or did not change their daily cigarette consumption as compared to baseline.

For the secondary outcomes, the self-reported quit rate in the three groups at 2- (TEL: 23.1%, SMS: 19.7%, CONTROL: 23.0%; P for TEL versus CONTROL = 0.40, P for SMS versus CONTROL = 0.20) and 12-month (TEL: 19.5%, SMS: 17.9%, CONTROL: 18.2%; P for TEL versus CONTROL = 0.35, P for SMS versus CONTROL = 0.40) follow-up showed no significant difference. The biochemically validated quit rate among the three groups at 12-month follow-up was similar. At 6-month follow-up, the rate of quit attempt (including quitters) in the three groups was 44.1, 50.1 and 47.9%, respectively. 39.1% of the TEL group, 41.2% of the SMS group and 36.7% of the CONTROL group reported reduction in daily cigarette consumption by 50% or more (including quitters). These differences were insignificant at all the follow-ups (all P > 0.025) (Table II).

Exploratory analyses

By the end-of-treatment approach, the multivariate logistic regression model showed that the abstinence in the TEL group [adjusted odds ratio (OR) = 1.46, 95% CI 0.97–2.20, P = 0.07) and the SMS group (adjusted OR = 1.26, 95% CI 0.83–1.91, P = 0.27) was higher than the CONTROL group, but the differences were insignificant. When we pooled the self-reported quitting at 2-, 6- and 12-month follow-up using the GEE model, the TEL group had higher abstinence than the CONTROL group, with marginal significance (adjusted OR = 1.38, 95% CI = 1.01–1.88, P = 0.04). (Table III) The SMS group and the CONTROL group showed no significant difference in abstinence (adjusted OR = 1.15, 95% CI = 0.83–1.59, P = 0.39).

Table III.

Odds ratios (95% confidence interval) of self-reported abstinence from logistic regression model and generalized estimating equation model (GEE) (by intention-to-treat analysis)

	Model 1	Model 2	Model 3
	Logistic regression (n = 987)	GEE (n = 987)	GEE (n = 957)
Intervention
TEL group	1.46 (0.97, 2.20)	1.38 (1.01, 1.88)*	1.58 (1.15, 2.15)**
SMS group	1.26 (0.83, 1.91)	1.15 (0.83, 1.59)	1.17 (0.84, 1.61)
CONTROL group	1.00	1.00	1.00
Perceived importance of quitting, (0–10)a	1.09 (1.00, 1.19)*	1.09 (1.02, 1.17)**	1.08 (1.01, 1.15)*
Perceived difficulty in quitting, mean (0–10)a	1.17 (1.08, 1.26)**	0.88 (0.84, 0.92)***	0.88 (0.84, 0.92)***
Perceived confidence in quitting, mean (0–10)a	0.88 (0.83, 0.93)**	1.19 (1.12, 1.26)***	1.20 (1.13, 1.27)***
Daily cigarette consumption at baseline
1–10	1.00	1.00	1.00
11–20	0.54 (0.35, 0.83)**	0.60 (0.43, 0.84)**	0.60 (0.42, 0.84)**
>20	0.41 (0.19, 0.86)*	0.65 (0.36, 1.16)	0.65 (0.36, 1.16)

Notes: Model 1: Multiple logistic regression model; Dependent variable is the self-reported 7-day PP of abstinence at the 6-month follow-up. Model 2: Generalized estimation equation (GEE) model; Dependent variable is the self-reported 7-day point prevalence of abstinence at all follow-ups. Model 3: Generalized estimation equation (GEE) model; Dependent variable is the self-reported 7-day point prevalence of abstinence at all follow-ups; Excluding subjects in TEL and SMS groups without receiving baseline interventions. All models were adjusted for baseline factors sex, age group, education level, marital status, having children, employment status, nicotine dependency, quitting history and intention to quit smoking.

^aAdjusted odds ratio per unit increase.

*P < .05; *P < 0.01; ***P < 0.001.

Sensitivity analysis

Similar findings were observed when we repeated the data analyses with the exclusion of the participants who did not receive telephone counselling in TEL group (n = 28) or those who refused to receive SMS text messages in SMS group (n = 2). Based on the end-of-treatment approach, no significant difference was found when we compared the 6-month self-reported PP quit rate between the TEL and CONTROL group (TEL: 23.5%, CONTROL: 20.3%, adjusted OR = 1.10 95% CI 0.77–1.58, P = 0.34), as well as the SMS and CONTROL group (SMS: 20.7%, CONTROL: 20.3%, adjusted OR = 1.03 95% CI 0.71–1.50, P = 0.39). The GEE model showed similar significant result with a greater odds ratio for the TEL group (adjusted OR = 1.58, 95% CI = 1.15–2.15, P < 0.01), but the adjusted odds ratio was insignificant for the SMS group (1.17, 95% CI = 0.84–1.61, P = 0.35) (Table III).

Perceived importance, difficulty and confidence to quit

In a scale of 0 (minimum) to 10 (maximum), the mean score of perceived importance to quit at 2, 6 and 12 months was similar to the baseline for all the three groups. At all the follow-ups, the score was also similar among the three RCT arms (all P > 0.05) (Fig. 2).

Fig. 2.

Perceived importance to quit at baseline, 2-, 6- and 12-month follow-up (Scale 0–10, 0 lowest, 10 highest). Remark: TEL group: Brief telephone counseling; SMS group: Text messages sent through mobile phone; CONTROL group: No counseling and text messages.

The mean score of perceived difficulty for all RCT groups significantly decreased from baseline to 12 months (P < 0.05). The mean score among the three RCT arms was similar at all follow-ups, except that the mean score for SMS group (6.27) was greater than the CONTROL group (5.25) at 6 months (P < 0.01) (Fig. 3).

Fig. 3.

Perceived difficulty to quit at baseline, 2-, 6- and 12-month follow-up (Scale 0–10, 0 lowest, 10 highest). Remark: TEL group: Brief telephone counseling; SMS group: Text messages sent through mobile phone; CONTROL group: No counseling and text messages.

For TEL group, the mean score of perceived confidence significantly increased from 6.02 at baseline to 7.09 at 2 months, 6.78 at 6 months and 6.82 at 12 months (P < 0.01). For SMS and CONTROL group, the mean score increased from baseline to 2 months, but then fell down at 6 months (P < 0.01). At 12 months, the mean scores for the three RCT groups were similar (P- > 0.05). Hence, the perceived confidence of participants in all RCT groups increased after joining the Contest and such increase was sustained at 6- and 12-month in the TEL group only (Fig. 4).

Fig. 4.

Perceived confidence to quit at baseline, 2-, 6- and 12-month follow-up (scale 0–10, 0 lowest, 10 highest). Remark: TEL group: Brief telephone counseling; SMS group: Text messages sent through mobile phone; CONTROL group: No counseling and text messages.

Discussion

Summary of findings

The brief telephone counselling and text messages, in addition to the lucky draw prizes, were feasible in the Quit to Win Contest, but no significant difference in the quit rate, proportion of smoking reduction by 50% or more, and proportion of initiating quit attempt(s) in the two intervention groups compared to the control group was found. When abstinence at all three follow-ups was modelled with GEE model simultaneously, the brief smoking cessation counselling via telephone increased abstinence by 38% with marginal significance.

Interpretation

The quit rate at the three follow-ups between the TEL group and the CONTROL group was insignificantly different, but the GEE model showed that the brief telephone counselling had an overall positive effect on abstinence. The result difference was not unexpected because the former analysis only looked into the abstinence at one particular follow-up, while the latter obtained the odds ratios representing the average intervention effect across time [27]. Therefore, the brief telephone counselling, which required much less labour and resources than a clinic-based cessation programme, might have a small effect on abstinence during the follow-up period. The small effect size might be due to the brief content of counselling, and there might be a time lag between the telephone counselling and the actual quit day. Also, the Quit to Win Contest had an overall high quit rate, which was about 20%, suggesting that the benefit from adding a brief intervention was not clear. Therefore, participation in the Quit and Win contest potentially aroused the interest of a large number of smokers to initiate a quit attempt. Future contests should consider adding and evaluating intensive interventions to assist smokers to quit such as medications and longer or more counselling sessions.

The present study found a significantly small impact of the brief counselling with the AWARD protocol, compared to delivery of a self-help booklet. It supported previous studies that using brief counselling such as the AWARD and the ‘5 A’s’ prompted quit attempt and increased abstinence [18, 20, 23]. The AWARD protocol takes less than a minute to complete, and does not require intensive training about the knowledge in smoking cessation for the implementation. Our findings also supported that brief advice can be used to help a large number of smokers who do not proactively seek smoking cessation services. As the protocol can be used by minimally trained people, future explorations on how to promote it to the public and applying it in other settings are warranted.

Our study did not find an additional effect of the eight short one-way text messages through mobile phone. A recent review of text messaging-based smoking cessation studies suggested a frequent schedule of text messages (e.g. one message per day) and a long period of receiving text messages (up to 26 weeks) were beneficial [28]. Another study suggested that receiving text messages when they were at high risk to smoke increased abstinence [29]. Simple real-time feedback system embedded in the messaging service was beneficial to the smokers [30]. Several studies found that the effect size (i.e. risk ratio of abstinence) for receiving text messages with higher intensity (at least five messages per day for 6 weeks) and a real-time feedback system ranged from 2.16 to 2.34 [28, 30–33]. However, the intensity of our messaging service was similar to a previous study which sent only one message to the smoker per week and yielded an insignificant difference (OR = 0.97, P = 0.40) in the rate of quit attempt compared with no text messages [34]. These findings suggested that a low intensity of short messaging services had no significant effect to increase abstinence. A real-time feedback messaging system is also recommended. Further studies are needed to understand the experience and reaction of smokers when they receive these messages.

This study had several limitations. First, only 27 and 24% of the self-reported quitters participated in the biochemical validation at 6- and 12-month follow-ups, respectively, even though they were required to pass the biochemical validation before they could enter into the lucky draw. Second, the retention rates at 6- and 12-month follow-ups were 70 and 65%, respectively, which were lower than our expectation (90%). The relatively low retention rate might underestimate the impact of the intervention when all participants who were lost to follow-up were assumed current smokers. Third, in our power calculations, we overestimated the effect size of the two intervention groups, thus our calculated sample size might have been under-powered to assess the statistical differences between the intervention groups and the control group.

Conclusions

The present study has shown some suggestive evidence that an additional brief telephone counselling with the AWARD protocol might have a small but positive adjunct effect in increasing the quit rate in the participants of the Quit to Win Contest. The eight SMS messages of smoking cessation did not have significant impact on abstinence. The Quit and Win contests can provide a good opportunity to attract smokers from the community. Further studies are necessary to test the additional impact of intensive counselling and interactive text messaging over Quit and Win contest to increase the quit rate.

Funding

This study was funded by the Hong Kong Council on Smoking and Health (COSH). The chairman (Lisa Lau) and the executive director (Vienna Lai) of the COSH are the co-authors of this study.

Conflict of interest statement

Prof. Tai-hing Lam is the principal investigator of the FAMILY project, which was funded by the Hong Kong Jockey Club Charities Trust. All other authors do not have connection with the tobacco, alcohol, pharmaceutical or gaming industries, and nobody was substantially funded by these organizations.

Supplementary data

Supplementary data are available at Health Education Research online