In 2010, Health Canada estimated that 4.8 million (17% of) Canadians 15 years or older were smokers.1 Cigarette smoking increases the risk of complications in patients undergoing surgery2–5 and even increases risk of perioperative death.6,7 Postoperative respiratory complications and poor wound healing in particular tend to be higher in smokers compared with nonsmokers.3–5,8 Therefore, it is preferable that patients undergoing surgery do not smoke.
A surgical encounter with the health care system has been described as a “teachable moment” that may motivate patients to engage in permanent smoking cessation and gain the associated health benefits of long-term smoking cessation.2,9 Despite this information, most anesthesiologists do not routinely offer smoking cessation advice to their patients, citing lack of time and training as barriers.10,11 A Canadian cohort study12 concluded that the preadmission clinic is a feasible location in which smoking cessation programs can be offered, but that there are significant logistical barriers to implementation. The cost of a designated smoking cessation nurse, used in previous perioperative smoking cessation trials,13–16 poses a significant barrier in real-world implementation of perioperative smoking cessation programs. A study was successful in improving counseling rates with the use of a preexisting quitline17 and offers a low-cost method of encouraging smoking cessation perioperatively.
A Cochrane systematic review including 8 trials demonstrated that preoperative smoking interventions are effective for changing smoking behavior perioperatively and may reduce postoperative morbidity,18 with several trials showing that even short-term preoperative smoking cessation interventions, particularly those started >4 weeks preoperatively, can reduce postoperative complications by up to 20% to 34%.13–15,19 Despite general agreement that a longer duration of preoperative abstinence is more beneficial, the optimal duration of smoking cessation preoperatively remains unsettled20–22 and must be balanced by the administrative difficulty in coordinating visits to the preadmission clinic well in advance of surgery. A review concluded that implementation of smoking cessation programs 3 to 8 weeks preoperatively are so cost-effective in reducing postoperative complications, that they are a matter of quality management.23 Nevertheless, it remains unclear what type of perioperative smoking cessation intervention would promote both short- and long-term smoking abstinence, yet be cost-effective enough to be implemented routinely in most preadmission clinics.
In this study, the hypothesis was that a preoperative smoking cessation intervention (nicotine replacement, brief intervention by a preadmission nurse, brochures, and a referral to the Smokers’ Helpline) in patients undergoing elective surgery, initiated at least 3 weeks preoperatively, would reduce nicotine use 24 hours preoperatively as measured by exhaled carbon monoxide (CO) levels. The secondary objectives were to compare intraoperative and immediate postoperative complication rates, length of stay in the postanesthetic care unit (PACU), and 30-day abstinence rates.
This was a single-center, randomized clinical trial conducted at St. Joseph’s Hospital (SJH), an ambulatory and short-stay (with anticipated surgical inpatient stays <3 days) surgical facility in London, Ontario, Canada, from October 2010 to May 2012. Approval for this trial was obtained from the University of Western Ontario Research Ethics Board and was registered at ClinicalTrials.gov (NCT01260233). Written informed consent was obtained from all subjects.
All patients scheduled for elective surgery at SJH and having a preadmission clinic appointment at least 3 weeks before their surgical date were screened via the preoperative questionnaire for smoking status. Three weeks was chosen as the preoperative recruitment time to accommodate the scheduling concerns of a busy preadmission clinic, and because 2 weeks has been shown to be insufficient to prevent postoperative complications,13 whereas 4 weeks and longer have resulted in reduced complications.14,15 Patients meeting inclusion criteria were informed about the study and provided with a written letter of information during their preadmission visit. Eligible patients were current daily smokers (>2 cigarettes daily and having smoked within the last 7 days) older than 18 years, who presented to the preadmission clinic at least 3 weeks preoperatively. Any type of elective surgery was eligible, with the primary types of procedures performed at SJH being general surgery, gynecologic, urologic, ophthalmologic, otolaryngologic, and orthopedic. Exclusion criteria were younger than 18 years, pregnancy, breastfeeding, poor proficiency in the English language, active participation in another smoking cessation trial, and inability to consent due to severe mental illness or dementia. In addition, patients with allergy to nicotine or Nicoderm®, and those with unstable angina or unstable arrhythmia were excluded.
Randomization was performed by the nurses in the preadmission clinic on the day of enrollment after the interested participants gave verbal and written informed consent. Randomization was computer-generated in randomly permuted blocks of sizes 2, 4, and 6 using the ralloc program24 in Stata version 11 for Mac OS X (StataCorp LP, College Station, TX). Patients were randomized in a 1:1 ratio to either the intervention or the control group, with allocation concealed using consecutively numbered, sealed, opaque envelopes. With the exception of the preadmission nurse, all treating physicians and nurses, research assistants, and outcome assessors were blinded to group allocation.
Patients randomized to the control arm received standard care, meaning they received inconsistent perioperative smoking cessation advice from nurses, surgeons, or anesthesiologists, but no further study-specific smoking cessation intervention. Participants in the control group were not discouraged from using perioperative smoking cessation aids and could still obtain brochures on request.
For patients randomized to the intervention group, the smoking cessation program was started on the day of enrollment and included a brief (<5 minutes) counseling session by a trained preadmission nurse regarding smoking cessation. Training of preadmission nurses consisted of a 1-hour group session on brief intervention with a provincially funded Smokers’ Helpline representative, provided at no cost by this organization. Nurses who missed the session, or those who began working after the session was held, were trained by a designated nurse who did attend. Patients were provided brochures on smoking cessation from the Canadian Cancer Society (see Supplemental Digital Content 1, https://links.lww.com/AA/A553) and a specific SJH Stop Smoking for Safer Surgery brochure (see Supplemental Digital Content 2, https://links.lww.com/AA/A554) prepared by SJH doctors, nurses, and pharmacists. In addition, a referral was faxed to the Canadian Cancer Society’s Smokers’ Helpline, a national telephone hotline that provides free and confidential services to smokers (see Supplemental Digital Content 3, https://links.lww.com/AA/A555). Patients also received a magnet with the Smokers’ Helpline information (see Supplemental Digital Content 4, https://links.lww.com/AA/A556). Once referred, the Smokers’ Helpline initiated contact (up to 4 attempts) with the patient, and subsequent counseling was as agreed on by the patient, but generally aimed to have at least 4 contacts with each patient. The Smokers’ Helpline was aware that patients referred to them were part of a research study and were aware of the date of surgery. All patients in the intervention arm were given a 6-week supply of free transdermal nicotine replacement therapy (Nicoderm®) along with written medication information (see Supplemental Digital Content 5, https://links.lww.com/AA/A557). For smokers of 10 cigarettes per day or more, a 4-week supply of 21 mg/d, 1-week supply of 14 mg/d, and 1-week supply of 7 mg/d patches were provided. Smokers of <10 cigarettes per day were supplied with 4 weeks of 14 mg/d patches and 2 weeks of 7 mg/d patches.
Recorded Data at Baseline
On inclusion in the study and before randomization, each patient had baseline data collected in the preadmission clinic, including demographics, any known cardiopulmonary comorbidities, and smoking habits. A baseline level of exhaled CO was obtained (piCO+™ Smokerlyzer®, Bedfont Scientific Ltd, Kent, England), and the Fagerström Tolerance Questionnaire25 was used to assess nicotine dependence.
The primary outcome of this study was self-reported abstinence from smoking for at least 7 days before surgery combined with an exhaled CO of ≤10 ppm on the day of surgery. Exhaled CO has a half-life of 2 to 8 hours and thus confirms abstinence for the preceding 6 to 24 hours before surgery.26
Secondary outcomes were:
- Inaccurately reported preoperative smoking cessation (self-reported 7-day abstinence with exhaled CO >10 ppm)
- Self-reported preoperative smoking reduction (report of smoking cigarettes 50% or less of initial self-report on the day of surgery)
- A composite of all intraoperative and immediate postoperative complications (those occurring in the PACU), defined in Table 1
- Total duration of care in the PACU and time until PACU discharge readiness, based on the modified Aldrete score (patients bypassing the PACU were not included)
- Unanticipated hospital admission (patients scheduled for day surgery and subsequently admitted to hospital)
- Hospital length of stay for inpatients
- Self-reported smoking cessation 7 days before the 30-day postoperative phone call
- Self-reported smoking reduction (by ≥50% of baseline) at the time of the 30-day postoperative phone call
Participants underwent surgery and anesthesia in accordance with hospital and individual physician practices. The anesthesiologists, who were blinded to group allocation, recorded the occurrence of any intraoperative complications by completing a short questionnaire, and blinded PACU nurses reported any immediate postoperative complications in a similar fashion. Anesthesiologists and PACU nurses were asked to provide as many details as possible with respect to the nature of the complication. All reported complications were reviewed by a blinded author, who then sought 2 other blinded authors’ opinions and decided by consensus if they felt it should not have been included. All outcome assessment was done before unblinding of data. PACU length of stay and discharge-readiness time, as well as hospital length of stay, were obtained from the patients’ charts.
Patients were contacted by blinded telephone interviewers 30 days after their date of surgery. During the interview, they were asked about their current smoking habits or quit date. Patients were also asked about the occurrence of any postoperative complications, unscheduled medical visits as a result of the surgery, and whether they felt well-supported in their attempts to quit. Patients who were unable to be reached after at least 10 attempts were considered to be lost to follow-up. One year postoperative follow-up calls inquiring about smoking habits or quit date are ongoing and are not included in this report.
The primary outcome was the effect of the smoking cessation intervention on preoperative rates of smoking cessation. The power calculation was based on previous studies, which had shown an absolute difference in smoking cessation rates between intervention and control groups to be 13% to 76%, with quit rates in the control groups ranging from 7.7% to 65%.13,14,27,28 The baseline quit rate was set at 20%, and the treatment effect was estimated to be an absolute increase in quit rate of 20% compared with the control group (quit rate in the intervention group 40% vs 20% in the control group). Accepting a 2-tailed α error of 5% and a β error of 20%, 158 patients (79 per group) were needed to achieve a proper sample size. To account for dropout or missing data, we elected to recruit 84 patients per group.
The trial was analyzed as an intention-to-treat trial. No adjustments for multiple comparisons were made, because all outcomes had been prespecified and were limited to a relatively small number.
Descriptive statistics were calculated for baseline demographic variables. Categorical secondary outcomes compared between groups (analyzed using Fisher exact test) included the proportion of patients having a reduction in smoking, the proportion of patients with a lower exhaled CO level on the day of surgery compared to baseline, the number of unanticipated hospital admissions, and the proportion of patients experiencing a complication intraoperatively, postoperatively, or both. Continuous secondary outcomes compared between groups included the number of days without smoking preoperatively, the average number of cigarettes per day, the exhaled CO on the day of surgery, and the duration of surgery. Histograms were constructed to visually assess whether or not continuous outcomes were approximately normally distributed. If they were, they were analyzed using Student t test and otherwise they were analyzed using the Wilcoxon rank sum test. If continuous variables were nonnormally distributed, 95% confidence intervals (CIs) of the difference in medians between groups were estimated using bootstrapping with 10,000 replications (percentile CI). Since the type of surgery performed could plausibly affect the duration of stay in the PACU, the time until PACU discharge readiness was compared between groups using a Cox regression model, adjusting for the type of surgery. The time until discharge readiness was graphically displayed using a Kaplan-Meier plot.
A 2-tailed P value of <0.05 was considered significant. Stata version 12.1 for Mac OS X (StataCorp LP) was used for all data management and analyses.
Between October 2010 and March 2012, 168 patients were recruited into the study. Follow-up for the primary outcome was completed in April 2012. During recruitment, 12,274 patients presented to the preadmission clinic. Of these, 1725 (14%) were self-identified smokers on their preoperative questionnaires. Of these self-identified smokers, only 595 were booked at least 3 weeks preoperatively and were thus further assessed for eligibility. For details, including reasons for missing data, see Consolidated Standards of Reporting Trials (CONSORT) flow chart in Figure 1.
Baseline patient characteristics are presented in Table 2. Age, gender and body mass index, types of surgery, and smoking habits were balanced between groups. Current diseases were slightly unevenly distributed, with more diabetes, hypertension, and heart disease in the intervention group.
The outcomes according to intention-to-treat are presented in Table 3. Preoperative smoking cessation in the intervention group (combined self-reported 7-day abstinence and 6- to 24-hour abstinence detected biochemically with exhaled CO) was significantly more frequent than smoking cessation in the control group. The relative risk for the primary outcome was 4.0 (95% CI, 1.2–13.7), corresponding to 1 additional patient quitting smoking for every 9.3 patients exposed to the smoking cessation intervention (number needed to treat 9.3; 95% CI, 5.2–44.6). Inaccurate self-reporting (statement of 7-day abstinence, but exhaled CO >10 ppm) was low and similar in both groups: 6% and 7% in the control and intervention groups, respectively (P = 1.00). The intervention group had a higher number of patients who reduced smoking compared with the control group.
The overall rate of combined intraoperative and immediate postoperative complications was not significantly different between groups (16.7% for the control group and 13.1% for the intervention group). Unanticipated hospital admission was rare (2.6% for the control group and 2.5% for the intervention group), and there was no statistically significant difference between groups. For the 44 nonambulatory patients (20 in the intervention group and 24 in the control group), hospital lengths of stay were short (2.1 days for the control group and 1.75 days for the intervention group) and not statistically significantly different between groups.
As expected, due to randomization, duration between preadmission clinic visit and surgical date (wait time for surgery), ASA physical status, anesthesia type, and duration of surgery were not significantly different between groups (Tables 3 and 4).
The time until PACU discharge readiness was significantly lower in the intervention group, as illustrated in the Kaplan-Meier plot (Fig. 2). Anonymized raw data and all statistical analyses are available as online supplemental content (see Supplemental Digital Content 6, https://links.lww.com/AA/A558, and 7, https://links.lww.com/AA/A559).
Patients were asked to contact the study pharmacist if there were any concerns with the use of the nicotine replacement patch. There were no adverse events reported to the pharmacist. However, 1 patient did reveal to the research assistant on the day of surgery that she did not use the patch due to a minor skin reaction that resolved spontaneously with discontinuation of the patch. This was also the only case of unintentional unblinding of the data collector.
Smokers’ Helpline Data
Of the 84 patients allocated to the intervention group, the Smokers’ Helpline was able to establish contact with 44 patients (52%), as shown in Figure 3. Services provided to these patients on first contact and total number of contacts are outlined in Table 5. The average length of the first contact was 17 minutes (SD 8), and the average length of subsequent contacts for those with 2 or more contacts was 9 minutes (SD 4).
30-Day Follow-Up Data
At follow-up 30 days postoperatively, self-reported 7-day point-prevalence abstinence was stated by 22 patients (28.6%) in the intervention group compared with 8 patients (11%) in controls (relative risk 2.6; 95% CI, 1.2–5.5; P = 0.008), as shown in Table 6. Patients in the intervention group were also more likely to report feeling well-supported in quitting around the time of surgery (83% in the intervention group compared with 49% in the control group, relative risk 1.69; 95% CI, 1.3–2.2; P < 0.0005). There were no differences in self-reported complications or unscheduled medical visits during the postoperative period.
This study demonstrated that patients receiving brief counseling in the preadmission clinic, brochures, nicotine replacement therapy, and a referral to a national telephone counseling hotline are more likely to quit and reduce smoking perioperatively compared with those receiving standard care.
One of the strengths of this study is the pragmatic nature of the intervention. Unlike previous more time-consuming studies,13–15 which required intensive face-to-face counseling, this study relied on preexisting infrastructure, including preadmission nurses and the Smokers’ Helpline, to deliver the information and/or counseling. The investigators’ and research assistant’s interaction with the patients in this study was solely for the purpose of informed consent and data collection and not for delivery of the intervention itself. This should make real-world implementation of the intervention more feasible, with no additional personnel costs, while still providing more intensive intervention than some of the brief interventions shown in a Cochrane meta-analysis18 to be less effective in long-term smoking cessation than high-intensity interventions.
This trial also addressed the difficulty in encouraging patients to contact a smoker’s helpline, such as was encountered in a cohort study.12 By faxing a referral to the helpline, which could then initiate contact with patients, 52% of the intervention group study participants obtained additional information and/or counseling by phone.
While this study did not rigorously investigate overall postoperative complications, previous studies have shown a reduction in postoperative morbidity among patients who successfully achieve smoking cessation.14,15 However, these studies were of higher intensity, using regular face-to-face counseling, and were initiated earlier preoperatively, ranging 4 to 8 weeks. The optimal duration of cessation has not been established and although it is generally agreed that a longer period of preoperative smoking cessation is more beneficial,22,29 this must be balanced with the logistics of booking patients into a busy preadmission clinic well ahead of their surgical dates. In this study, despite strong efforts by the preadmission staff to book patients early, two thirds of self-identified smokers were booked <3 weeks preoperatively and thus ineligible for inclusion. Further studies are needed to more thoroughly investigate the impact of smoking cessation programs on postoperative complications, as this study included many ambulatory patients who have a low baseline risk of complications. As such, this study was underpowered to see differences in complications between groups. Future studies are still needed to further delineate the optimal timing of smoking cessation and the degree to which postoperative complications can be prevented.
One of the secondary outcomes investigated in this study was the effect of preoperative smoking cessation intervention on length of stay in the PACU. The intervention group had shorter times until PACU discharge readiness. The clinical importance of this finding is uncertain, as actual PACU discharge times were not different between groups. Further studies are needed to assess the reproducibility and clinical importance of this finding.
The ability to detect a difference in complications and overall hospital length of stay may have been limited by the patient population studied, which was largely ambulatory. Not only would overall rates of complications and hospital length of stay be lower among ambulatory patients, but these patients having relatively minor surgery may have also been less motivated in smoking cessation as compared with major cancer or cardiovascular operations, which have been shown to have high spontaneous quit rates.9
Our particular multifaceted intervention was chosen based on current literature demonstrating that addition of nicotine replacement therapy to counseling, and vice versa, improves smoking cessation rates over monotherapy alone, both in hospitalized patients30 and in the general population using a telephone quitline.31,32 One of the limitations of the use of the multimodal intervention is that it made it difficult to ascertain which component had the most significant effect on outcome. Future research could provide more detailed information on the use of the various components, particularly the nicotine replacement therapy and the Smokers’ Helpline, and how this affects smoking cessation.
Concerns have been expressed that short-term smoking cessation increases perioperative pulmonary complications despite the lack of substantiated evidence supporting this contention and a systematic review indicating that these concerns are indeed unfounded.33 This study, though underpowered to rigorously examine perioperative complications, did not detect any increase in intraoperative or immediate postoperative complications in the intervention group and will help to dispel this erroneous belief. In addition, follow-up at 30 days postoperatively did not show an increase in self-reported complications or unscheduled medical visits, although a limitation of the 30-day follow-up data is that it was self-reported and not confirmed with the chart or biochemical tests.
The external validity of this clinical trial may be limited by the large number of patients who refused to participate in the study. High refusal rates (28%–32%) have also been shown in previous perioperative smoking cessation studies.14,15 However, it is encouraging that while at least 1 previous study15 indicated that a large number of patients refusing to participate had no interest in giving up smoking, 32% of the patients refusing to participate in this study did express a desire to quit and it is possible they would have agreed to some of the interventions outside of a study environment. Nevertheless, it is unclear how generalizable these results are to the smoking population at large.
It is possible that the treatment effect observed might have been diminished by the control group being influenced to quit smoking during the process of informed consent, when the health benefits of smoking cessation were given as a possible benefit of participation. It seems unlikely, however, that the control group was influenced, given the low rate of smoking cessation in the control group (3.6%) compared with previous trials ranging from 7.7% to 65%.13,14,27,28
In summary, an easily implemented and inexpensive intervention to promote smoking cessation to surgical patients at least 3 weeks preoperatively resulted in improved smoking cessation and reduction rates on the day of surgery that were sustained at 30 days postoperatively. Moreover, the intervention group demonstrated shorter times until PACU discharge readiness. The smoking cessation intervention did not contribute to any increase in cardiopulmonary complications. This intervention, and its straightforward implementation, dispel frequently raised objections to more active participation of anesthesiologists in preoperative smoking cessation programs.
Name: Susan M. Lee, MD.
Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.
Attestation: Susan Lee has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Jennifer Landry, MD.
Contribution: This author helped conduct the study, analyze the data, and write the manuscript.
Attestation: Jennifer Landry has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Name: Philip M. Jones, MD, MSc (Clinical Trials).
Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.
Attestation: Philip Jones has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.
Name: Ozzie Buhrmann, BScPhm, RPh.
Contribution: This author helped conduct the study.
Attestation: Ozzie Buhrmann approved the final manuscript.
Name: Patricia Morley-Forster, MD.
Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.
Attestation: Patricia Morley-Forster has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
This manuscript was handled by: Peter S. A. Glass, MB, ChB.
Special thanks go to our research assistant Dr. Justin Mall. The authors would also like to thank all the preadmission and perioperative staff at SJH for their enthusiastic participation and the Canadian Cancer Society’s Smokers’ Helpline.
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