A planning intervention to quit smoking in single-smoking couples: does partner involvement improve effectiveness?

Figures & data

Figure 1. Flow-chart of the study sample. N represents the number of couples.

Table 1. Mean baseline characteristics for the dyadic and individual planning group.

Variables	Dyadic planning group		Individual planning group
	Smokers (n = 145)	Partners (n = 135)	Smokers (n = 167)	Partners (n = 150)
Male (%)	50.3	42.2	46.1	38.0
Age (years)	38.2 (11.7, 18-72)	39.2 (11.5, 20-71)	38.4 (11.4, 18-65)	37.9 (11.7, 19-70)
Relationship duration (years)*	12.0 (10.7, 1.0-49.3)	12.5 (10.8, 1.3-52.1)	12.9 (10.7, 1.0-47.0)	12.2 (10, 1.1-45.4)
Number of cigarettes smoked**	16.8 (9.2, 1-52)	--	17.0 (8.7, 2-55)	--
Relationship satisfaction***	6.8 (1.12, 1.3-8.0)	6.7 (1.14, 2.3-8.0)	6.8 (1.24, 0.8-8.0)	6.8 (1.09, 2.4-8.0)

Note. *DP: 134 partners, **DP: 137 smokers, IP: 158 smokers, ***DP: 136 smokers and 125 partners, IP: 154 smokers and 148 partners. Standard deviations and ranges are in brackets.

Table 2. Smoking behaviour at follow-up and smoking patterns in the diary as reported by smokers.

Smoking behaviour at follow-up	Dyadic Planning (n = 73)	Individual planning (n = 83)	Total (n = 156)	Diary smoking pattern (n = 142)
				Relapse (n = 74)	Intermittent (n = 37)	Quitters (n = 31)
‘I quit smoking since the intervention’	14 (19%)	13 (16%)	27 (17%)	4 (5%)	1 (3%)	17 (55%)
‘I smoked just a few cigarettes since the intervention’	12 (16%)	10 (12%)	22 (14%)	7 (10%)	5 (14%)	5 (16%)
‘I started smoking daily, but quit again’	7 (10%)	11 (13%)	18 (12%)	7 (10%)	7 (19%)	4 (13%)
‘I am smoking, but not daily’	7 (10%)	5 (6%)	12 (8%)	2 (3%)	8 (22%)	2 (7%)
‘I am smoking daily’	33 (45%)	44 (53%)	77 (49%)	54 (73%)	16 (43%)	3 (10%)
Smoking zero cigarettes	24 (33%)	25 (30%)	49 (31%)	11 (15%)	7 (19%)	22 (71%)

Table 3. Proportion of prolonged smoking abstainers (7, 14 and 21 subsequent days of reported not smoking) reported by smokers, and average daily relationship satisfaction per week of both members of the couples.

Smoking abstinence	Dyadic planning (n = 83)	Individual planning (n = 93)	Chi-Square	p
Week 1 (7 days)	15 (18%)	13 (14%)	0.143	.705
Week 2 (14 days)	10 (12%)	8 (9%)	0.222	.637
Week 3 (21 days)	4 (5%)	5 (5%)	Fisher's exact test	1.000
Relationship satisfaction Smokers	Dyadic planning (n = 83)	Individual planning (n = 92)	t	p	BCa 95% Confidence Interval of MD	d
Week 1	8.1 (1.5)	8.2 (1.6)	0.658	.511	[−0.32 to 0.64]	0.10
Week 2*	8.4 (1.4)	8.2 (1.6)	−0.692	.490	[−0.63 to 0.29]	0.11
Week 3**	8.4 (1.4)	8.2 (1.7)	−0.637	.525	[−0.69 to 0.36]	0.11
Partners	Dyadic planning (n = 82)	Individual planning (n = 91)	t	p	BCa 95% Confidence Interval of MD	d
Week 1	8.4 (1.4)	8.4 (1.3)	0.099	.921	[−0.37 to 0.36]	0.02
Week 2*	8.5 (1.3)	8.4 (1.3)	−0.505	.614	[−0.49 to 0.29]	0.08
Week 3**	8.5 (1.4)	8.3 (1.4)	−0.677	.500	[−0.63 to 0.30]	0.11

Note. Strict rules are applied for smoking: no relapses or missings are allowed. ^*DP: 72 smokers, 73 partners, IP: 83 smokers, 83 partners, **DP: 68 smokers, 68 partners, IP: 80 smokers, 78 partners. Standard deviations of relationship satisfaction are in brackets.

Table 4. Bootstrap regression model of number of cigarettes at follow-up (n = 144 smokers) and multilevel model of relationship satisfaction at follow-up (n = 167 subjects).

Number of cigarettes* Predictors	Estimate	Bias	SE	p	BCa 95% Confidence Interval
Constant	−0.63	0.06	2.42	.805	[−5.49 to 4.33]
Nr of cigarettes baseline	0.34	−8.37E − 5	0.11	.002	[0.16 to 0.56]
Intervention**	1.62	−0.04	1.29	.206	[−0.94 to 3.95]
Relationship satisfaction Predictors	Estimate	SE	t	p	95% Confidence Interval
Intercept	1.89	0.55	3.42	.001	[0.80 to 2.99]
Relationship satisfaction baseline	0.80	0.05	15.49	.000	[0.70 to 0.90]
Intervention**	−0.36	0.28	−1.30	.197	[−0.91 to 0.19]
Role***	−0.55	0.27	−2.04	.043	[−1.09 to −0.02]
Intervention*Role	0.29	0.18	1.65	.101	[−0.06 to 0.64]

Note. *R² = 0.14, F(2,142) = 11.83, p <.001. **Individual group = 1, Dyadic group = 2. ***1 = Smoker, 2 = Partner.

Data availability statement

The data that support the findings of this study are available from the corresponding author, Anne Buitenhuis, upon reasonable request.