Key Points
Question
Does smoking increase the risk of complications associated with head and neck microvascular reconstructive surgery?
Findings
This population database study of 2193 patients found that perioperative smoking was associated with increased rates of wound breakdown and reoperation within 30 days. The degree of risk did not correlate with number of pack-years smoked.
Meaning
Smoking cessation prior to head and neck free flap surgery may decrease postoperative morbidity.
Abstract
Importance
Smoking is a highly prevalent risk factor among patients with head and neck cancer. However, few studies have examined the association of this modifiable risk factor on postoperative outcomes following microvascular reconstruction of the head and neck.
Objective
To analyze the risk associated with smoking in patients undergoing free flap surgery of the head and neck.
Design, Setting, and Participants
In this retrospective, population, database study, the National Quality Improvement Program data sets from 2005 to 2014 were queried for all cases of head and neck surgery involving free flap reconstruction in the United States. The 2193 cases identified were stratified into smoking and nonsmoking cohorts and compared using χ2 and binary logistic regression analyses. Pack-years of smoking data were used to assess the degree of risk associated with a prolonged history of smoking. All analyses were conducted between January 2018 and June 2018.
Main Outcomes and Measures
Smoking and nonsmoking cohorts were compared for rates of demographic characteristics, comorbidities, and complications. Following correction for differences in patient demographics and comorbidities, smoking and nonsmoking cohorts were compared for rates of postoperative complications. Complication rates were further assessed within the smoking cohort by number of pack years smoked.
Results
Of the 2193 patients identified as having undergone free flap reconstruction of the head and neck, 624 (28.5%) had a history of recent smoking. After accounting for differences in demographic variables and patient comorbidities using regression analyses, smoking status was found to be independently associated with wound disruption (odds ratio, 1.74; 95% CI, 1.17-2.59; P = .006) and unplanned reoperation (odds ratio, 1.50; 95% CI, 1.15-1.95; P = .003). An analysis by pack-years of smoking showed that a longer smoking history was significantly associated with higher rates of numerous comorbidities but not with a corresponding increase in rates of complications.
Conclusions and Relevance
Smokers undergoing free flap reconstruction of the head and neck may be at significantly higher risk of postoperative wound disruption and subsequent reoperation. These risks were independent of pack-years of smoking history, suggesting that both risks were associated with perioperative smoke exposure, and preoperative smoking cessation may be of benefit.
Level of Evidence
NA.
This population database study uses 2005-2014 National Surgical Quality Improvement Program data to assess the risks associated with smoking among patients undergoing free flap reconstruction surgery of the head and neck.
Introduction
While the prevalence of cigarette smoking continues to decline, tobacco use remains the leading cause of preventable disease and death in the United States.1,2 The consequences of smoking on normal physiologic mechanisms have been well studied, and the carcinogenic properties are well understood. Cigarette smoking is the greatest risk factor for the development of head and neck cancer, responsible for an estimated 68% of cases.3 In addition, smokers have been shown to be worse surgical candidates than nonsmokers, with significantly higher rates of postoperative complications.4,5,6,7 In prior analyses, perioperative smoking has been shown to independently increase the risk of infection, wound complications, and general morbidity.4
In the surgical management of head and neck cancer, free flap reconstruction is a valuable tool for addressing large or complex deficits following tumor resection. These procedures often require a long operative course and carry inherently high rates of postoperative complications. Although the rate of flap failure is generally low (2%-7%), it is important to be able to identify patients who are at increased risk of this costly complication.8,9,10 The impact of smoking is of particular interest because a significant proportion of the patient population requiring free flap reconstruction is likely to carry this risk factor. Furthermore, smoking is known to be associated with vascular and coagulative pathology as well as with impaired wound healing, which may have implications for the integrity of the microvascular anastomosis.11,12,13 However, there is a dearth of research regarding the implications of preoperative smoking on head and neck free flap reconstruction outcomes, with studies limited to single-institution series. Therefore, we sought to use the American College of Surgeons’ National Surgical Quality Improvement Program (NSQIP) database to generate a robust, population-based analysis of the implications of smoking status on morbidity and mortality among patients undergoing free flap surgery of the head and neck.
Methods
This retrospective, population, database analysis was performed using 2005-2014 NSQIP participant user files. This database was queried using the Current Procedural Terminology (CPT) codes given in Table 1 for all cases of microvascular free flap surgical procedures. Cases were selected for inclusion when the procedure was performed by an otolaryngologist or when the primary surgical site was identified as the head and neck. Cases with free flaps not performed by otolaryngologists were manually screened for surgical site using CPT codes, the International Classification of Diseases, Ninth Revision, codes for postoperative diagnosis, or both. Patients were stratified into smoking and nonsmoking cohorts, with smokers defined by NSQIP as patients who have “smoked cigarettes in the year prior to admission to surgery.” Per Rutgers New Jersey Medical School (Newark) guidelines, this analysis was determined to be exempt from the need of obtaining institutional review board approval or informed patient consent because the data were collect from a deidentified database.
Table 1. CPT Codes and Definitions of Flap Procedure Type.
| Flap Type, CPT Code | Description of Flap Procedure Associated With CPT Code |
|---|---|
| Cutaneous | |
| 15757 | Free skin flap with microvascular anastomosis |
| Fascial | |
| 15758 | Free fascial flap with microvascular anastomosis |
| Muscle | |
| 15756 | Free muscle flap with or without skin graft with microvascular anastomosis |
| 15842 | Graft for facial nerve paralysis, free muscle flap by microsurgical technique |
| Bone | |
| 20955 | Bone graft with microvascular anastomosis; fibula |
| 20956 | Bone graft with microvascular anastomosis; iliac crest |
| 20962 | Bone graft with microvascular anastomosis; other than iliac crest, metatarsal, or great toe |
| 20969 | Free osteocutaneous flap with microvascular anastomosis; other than iliac crest, metatarsal, or great toe |
| 20970 | Free osteocutaneous flap with microvascular anastomosis; iliac crest |
Abbreviation: CPT, Current Procedural Terminology.
The groups were first compared for rates of demographic variables and patient comorbidities. These preoperative characteristics included obesity (body mass index calculated as weight in kilograms divided by height in meters squared >30), current alcohol use (>2 drinks per day in the 2 weeks before admission), weight loss (>10% in the 6 months prior to surgery), hypertension (requiring medication), disseminated cancer, corticosteroid use (<30 days prior to surgery), preoperative chemotherapy or radiation, nonindependent functional status, and a number of additional preexisting medical conditions, which are given in Table 2.
Table 2. Patient Demographic, Comorbidity, and Operative Characteristics.
| Characteristic | Patients, No. (%) | P Value | |
|---|---|---|---|
| Nonsmoker (n = 1569) | Smoker (n = 624) | ||
| Age group, y | |||
| ≤40 | 120 (7.6) | 45 (7.2) | .73 |
| 41-60 | 506 (32.2) | 334 (53.5) | <.001 |
| 61-80 | 805 (51.3) | 235 (37.7) | <.001 |
| >80 | 138 (8.8) | 10 (1.6) | <.001 |
| Age, mean (SD), y | 62.8 (14.1) | 57.6 (11.1) | <.001 |
| Male | 984 (62.7) | 449 (72.1) | <.001 |
| Race/ethnicity | |||
| White | 1202 (89.3) | 460 (87.5) | .25 |
| Black | 83 (6.2) | 59 (11.2) | <.001 |
| Other | 61 (4.5) | 7 (1.3) | .001 |
| Comorbidity | |||
| Obesity | 371 (23.7) | 76 (12.2) | <.001 |
| Diabetes | 221 (14.1) | 36 (5.8) | <.001 |
| Alcohol | 31 (5.3) | 48 (23.6) | <.001 |
| Weight loss | 118 (7.5) | 102 (16.3) | <.001 |
| Previous cardiac surgery | 28 (4.8) | 9 (4.5) | .83 |
| COPD | 69 (4.4) | 84 (13.5) | <.001 |
| Dyspnea | 95 (6.1) | 88 (14.1) | <.001 |
| Previous PCI | 33 (5.7) | 12 (5.9) | .90 |
| Hypertension | 769 (49.0) | 266 (42.6) | .007 |
| PVD | 7 (1.2) | 5 (2.5) | .21 |
| Prior stroke | 20 (3.4) | 10 (5.0) | .34 |
| Disseminated cancer | 102 (6.5) | 64 (10.3) | .003 |
| Corticosteroid use | 61 (3.9) | 16 (2.6) | .13 |
| Bleeding disorder | 38 (2.4) | 14 (2.2) | .80 |
| Chemotherapy | 29 (5.0) | 10 (5.0) | .98 |
| Prior radiation | 10 (1.7) | 4 (2.0) | .81 |
| Prior operation | 34 (5.9) | 10 (5.0) | .66 |
| Anemia | 392 (43.1) | 166 (39.6) | .24 |
| Dependent functional status | 36 (2.3) | 15 (2.4) | .88 |
| Flap type | |||
| Cutaneous | 595 (37.9) | 234 (37.5) | .86 |
| Fascial | 207 (13.2) | 75 (12.0) | .44 |
| Muscular | 420 (26.8) | 180 (28.9) | .55 |
| Osseous | 347 (22.1) | 135 (21.6) | .32 |
| Total operative time, mean (SD), min | 547 (179) | 567 (179) | .02 |
Abbreviations: CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; PCI, percutaneous coronary intervention; PVD, peripheral vascular disease; TIA, transient ischemic attack.
Smoking and nonsmoking cohorts were then compared for rates of 30-day postoperative complications. Surgical and medical complications as well as overall complication rates were compared between groups. Specific complications assessed included superficial and deep surgical site infection, wound disruption (spontaneous reopening of a surgically closed wound), nerve injury, flap failure, stroke (causing neurological deficit), bleeding (requiring blood transfusion within 72 hours of the postsurgical period), ventilator use for more than 48 hours, and others identified in Table 3. Because bleeding requiring transfusion represented the vast majority of postoperative complications, and may not necessarily represent a complication in a free flap procedure, it was not included in the calculation of total surgical and overall complication rates. In addition, rates of 30-day mortality, unplanned readmission, reoperation, total operating time, and length of stay were assessed. The most common indications for reoperation were determined using the International Classification of Diseases, Ninth Revision, codes listed for postoperative diagnosis. Any indications accounting for greater than 1% of the population were included in Table 3.
Table 3. Postoperative Complication Rates in Head and Neck Free Flap Surgery.
| Complication | Patients, % | P Value | |
|---|---|---|---|
| Nonsmoker (n = 1569) | Smoker (n = 624) | ||
| Surgical complications, overalla | 260 (16.6) | 130 (20.8) | .02 |
| Superficial SSI | 113 (7.2) | 46(7.4) | .89 |
| Deep SSI | 95 (6.0) | 42 (6.8) | .45 |
| Wound disruption | 72 (4.6) | 55 (8.8) | <.001 |
| Bleeding requiring transfusion | 509 (32.5) | 228 (36.5) | .07 |
| Nerve injury | 1 (0.1) | 1 (0.2) | .50 |
| Flap failure | 34 (2.9) | 15 (3.3) | .72 |
| Medical complications, overall | 274 (17.5) | 109 (17.5) | >.99 |
| Pneumonia | 110 (7.0) | 38 (6.1) | .44 |
| Unplanned reintubation | 56 (3.6) | 13 (2.1) | .07 |
| Urinary tract infection | 24 (1.5) | 10 (1.6) | .90 |
| Deep vein thrombosis | 10 (0.6) | 4 (0.6) | >.99 |
| Renal insufficiency | 2 (0.1) | 0 | .37 |
| Pulmonary embolism | 11 (0.7) | 7 (1.1) | .32 |
| Ventilator >48 h | 100 (6.4) | 47 (7.5) | .33 |
| Acute renal failure | 1 (0.1) | 1 (0.2) | .50 |
| Stroke | 11 (0.7) | 4 (0.6) | .88 |
| Cardiac arrest requiring CPR | 13 (0.8) | 5 (0.8) | .95 |
| Myocardial infarction | 17 (1.1) | 5 (0.8) | .55 |
| Sepsis | 61 (3.9) | 30 (4.8) | .33 |
| Septic shock | 16 (1.0) | 4 (0.6) | .40 |
| Overall complicationsa | 442 (28.2) | 197 (31.6) | .11 |
| Unplanned reoperation | 238 (17.9) | 130 (24.8) | .001 |
| Hematoma or seromab | 63 (4.9) | 28 (5.4) | .74 |
| Mechanical graft issue (including embolus)b | 35 (2.6) | 18 (3.4) | .38 |
| Wound disruptionb | 23 (1.7) | 19 (3.7) | .02 |
| Infectionb | 23 (1.7) | 17 (3.2) | .08 |
| Unplanned readmission | 123 (7.8) | 57 (9.1) | .32 |
| 30-Day mortality | 16 (1.0) | 6 (1.0) | .90 |
Abbreviations: CPR, cardiopulmonary resuscitation; SSI, surgical site infection.
Does not include bleeding requiring transfusion.
Postoperative diagnosis code given for reoperation.
For all postoperative complications found to occur at significantly different rates between groups, a binary logistic regression model was generated to assess the relative risk independently associated with smoking status. All demographic and comorbidity variables shown in Table 2 that were found to be significantly different between groups were included in the regression model. Table 4 gives the odds ratios associated with smoking, with nonsmoking patients serving as the reference category. Regression models were generated for each statistically significant complication identified in Table 3. Comparisons of preoperative factors and postoperative complications (Tables 2 and 3) were analyzed using Pearson χ2 test, Fisher exact test, or independent 2-tailed t tests where appropriate. For variables missing data for a portion of cases, the valid percentages are recorded in Tables 2 and 3.
Table 4. Multivariate Logistic Regression for Postoperative Complications Following Head and Neck Free Flap Surgery.
| Complication | Odds Ratio (95% CI) | P Value |
|---|---|---|
| Wound disruption | 1.74 (1.17-2.59) | .006 |
| Unplanned reoperation | 1.50 (1.15-1.95) | .003 |
| Surgical complication | 1.27 (0.98-1.64) | .06 |
A subsequent analysis was conducted to assess the association of smoking history (using pack-years of smoking) with postoperative outcomes. Patients with available pack-years of smoking data were stratified into 4 cohorts: 15 or less pack-years, 16 to 30 pack-years, 31 to 45 pack-years, and more than 45 pack-years. These groups were compared using the Mantel-Haenszel test for trend across the 4 groups for the comorbidities and complications identified in Tables 2 and 3. Only those comorbidities found to positively trend with increasing pack-years smoked were included in Table 5. Because no complications were found to significantly trend across any of the 4 groups, the rates of wound disruption and reoperation and the overall rates of medical, surgical, and total complications are selectively given in Table 5. All statistical analyses were performed between January 2018 and June 2018 using SPSS, version 23 (IBM), and P < .05 was considered statistically significant.
Table 5. Comorbidities and Postoperative Complications Based on Pack-Years of Smoking.
| Comorbidity or Complication | Comorbid or Complication Rate, % | P Value | |||
|---|---|---|---|---|---|
| Pack-Years | |||||
| ≤15 (n = 95) | 16-30 (n = 95) | 31-45 (n = 77) | >45 (n = 128) | ||
| Comorbidity | |||||
| Dyspnea | 4 (4.2) | 6 (6.3) | 12 (15.6) | 22 (17.2) | .001 |
| COPD | 0 | 4 (4.2) | 10 (13.0) | 24 (18.8) | <.001 |
| Alcohol use | 10 (10.5) | 12 (12.6) | 13 (16.9) | 27 (21.1) | .02 |
| PVD | 0 | 1 (1.1) | 3 (3.9) | 6 (4.7) | .01 |
| Stroke | 1 (1.1) | 3 (3.2) | 7 (9.1) | 8 (6.3) | .03 |
| Weight loss | 9 (9.5) | 12 (12.6) | 11 (14.3) | 25 (19.5) | .03 |
| Complication | |||||
| Wound disruption | 2 (2.5) | 8 (8.3) | 4 (6.5) | 5 (4.0) | .21 |
| Reoperation | 17 (18.3) | 13 (13.8) | 13 (16.3) | 6 (4.9) | .08 |
| Total surgical complications | 20 (21.1) | 23 (24.2) | 14 (18.2) | 18 (14.1) | .10 |
| Total medical complications | 17 (17.9) | 11 (11.6) | 15 (19.5) | 28 (21.9) | .21 |
| Overall complications | 28 (29.5) | 27 (28.4) | 25 (32.5) | 35 (27.3) | .83 |
Abbreviations: COPD, chronic obstructive pulmonary disease; PVD, peripheral vascular disease.
Results
In total, 2193 patients were identified as having undergone a free flap reconstruction procedure of the head and neck. Of these patients, 624 (28.5%) were identified as smokers, and 1569 (71.5%) as nonsmokers. Smokers were found to be significantly younger (mean [SD], 57.6 [11.1] years vs 62.8 [14.1] years; P < .001), and more likely to be male (449 [72.1%] vs 984 [62.7%]; P < .001). Both patient groups were composed predominantly of white individuals, but the smoker group had a significantly higher proportion of black patients than the nonsmoker group did (59 [11.2%] vs 83 [6.2%]; P < .001).
Analyses of comorbidities (Table 2) revealed that smokers (n = 624) had significantly higher rates than nonsmokers (n = 1569) of dyspnea (88 [14.1%] vs 95 [6.1%]; P < .001), alcohol use (48 [23.6%] vs 31 [5.3%]; P < .001), weight loss (102 [16.3%] vs 118 [7.5%]; P < .001), and chronic obstructive pulmonary disease (COPD; 84 [13.5%] vs 69 [4.4%]; P < .001). However, nonsmokers were more likely to have diabetes (221 [14.1%] vs 36 [5.8%]; P < .001), hypertension (769 [49.0%] vs 266 [42.6%]; P = .007), and obesity (371 [23.7%] vs 76 [12.2%]; P < .001).
Overall, postoperative complications (Table 3) occurred in 639 patients (29.1%). Although smokers had a higher rate than nonsmokers of overall complications, this difference did not reach statistical significance (31.6% vs 28.2%; P = .11). The rate of total surgical complications was significantly higher in smokers (20.8% vs 16.6%; P = .02), who also had significantly higher rates of wound disruption (8.8% vs 4.6%; P < .001). In addition, smokers had higher rates than nonsmokers of unplanned reoperation (24.8% vs 17.9%; P = .001). By contrast, there was no significant difference in the rate of any medical complication between groups. Smokers were found to have a longer length of stay (12.2 days vs 10.9 days; P = .01) as well as higher rates of unplanned reoperation (24.8% vs 17.9%; P = .001). Rates of 30-day mortality were 1.0% in both groups. Multivariate analysis (Table 4) accounting for demographics and statistically significant comorbidities showed that smoking was independently associated with wound disruption (odds ratio, 1.74; 95% CI, 1.17-2.59; P = .006) and unplanned reoperation (odds ratio, 1.50; 95% CI, 1.15-1.95; P = .003) in free flap surgery. However, the risk of total surgical complications was no longer significantly associated with smoking (odds ratio, 1.27; 95% CI, 0.98-1.64; P = .06).
A total of 395 patients were included in the analysis examining pack-years of smoking (Table 5), with 95 patients (24.1%) in the cohorts comprising both 15 or fewer pack-years and 16 to 30 pack-years, 77 patients (19.4%) in the 31 to 45 pack-years cohort, and 128 patients (32.4%) in the cohort with more than 45 pack-years. The rates of numerous comorbidities, including dyspnea, COPD, alcohol use, peripheral vascular disease, prior stroke, or weight loss, significantly increased with increasing numbers of pack-years. However, there was no significant trend observed in the rate of any postoperative complication for total surgical, total medical, or overall complications with increasing number of pack-years (Table 5).
Discussion
Smoking is a known risk factor for a number of health-related consequences, and has been recognized as a contributing factor in postoperative morbidity. Preoperative tobacco use has specifically been shown to increase the risk of pulmonary, cardiac, neurological, and infectious complications.4,14 These effects are due to a release of reactive oxygen species, which cause damage at the cellular and tissue levels. Smoking also inhibits normal tissue perfusion and oxygenation, impairs immune system function, and disrupts collagen synthesis and cell repair.15 The association of smoking with postoperative complications in free flap reconstruction of the head and neck is of particular interest because smoking is known to be a major risk factor for the development of head and neck cancer.16 In addition, smoking has been shown to disrupt normal vascular physiology, which may compromise the integrity of the microvascular anastomosis.11,17
In the present analysis, we found that 28.5% of patients who underwent head and neck free flap surgery had smoked within the previous year. This is notably higher than the overall rate of smoking in the US, reported by the Centers for Disease Control and Prevention to be 16.8% in 2014.1 A number of significant differences were identified between smoking and nonsmoking cohorts, indicating a disparity in preoperative health status. Patients in the smoking group were a mean of 5 years younger than nonsmokers undergoing the same procedure; however, smokers had higher rates of disseminated disease as well as weight loss. Previous studies have shown that tobacco use is associated with increased cancer stage at the time of diagnosis in head and neck cancers overall and laryngeal cancer specifically.18,19 The smoking cohort also had significantly higher rates of alcohol use, which is another well-known risk factor in the development of cancer. Hashibe et al3 reported that 72% of all head and neck cancers are attributable to tobacco, alcohol, or both and combined use has a greater than multiplicative effect on the risk of development. Tobacco use was also associated with dyspnea and COPD in the present study, both of which are known complications of smoking.20
By contrast, nonsmokers were found to have significantly higher rates of obesity, diabetes, and hypertension, all of which are likely interrelated. This may in part reflect the trend in the rates of these chronic conditions with increasing age.21 In addition, it is well understood that smoking contributes to an increased resting metabolic rate and decreased caloric consumption secondary to appetite suppression.22,23 However, it is likely that additional factors are at play because smokers were found to have significantly higher rates of recent weight loss. This may suggest that a greater proportion of patients in the smoking cohort were experiencing cancer-associated cachexia, which is a product of more advanced disease in this cohort. In addition, a retrospective study on the need for enteral feeding in patients undergoing head and neck radiotherapy found that smoking increased the need for enteral nutrition, suggesting that smoking may exacerbate cancer-associated cachexia.24
The most dramatic difference in postoperative outcomes observed between groups in the present study was the rate of wound dehiscence, which occurred nearly twice as often in smokers than in nonsmokers. This was true even after correcting for differences between the 2 patient populations. This finding is in agreement with existing knowledge of the detrimental consequences of smoking on normal wound healing.25 This wound healing disruption is thought to be associated with the transient effects of tobacco smoke on tissue microvasculature, namely, decreased tissue oxygenation, which results in inhibition of reparative cell functions.26 Furthermore, the components of cigarette smoke, including carbon monoxide and hydrogen cyanide, work to diminish and inhibit oxidative metabolism and oxygen transport at the cellular level.13 Tobacco use has previously been shown to be associated with wound disruption in studies of other patient populations as well as in patients with head and neck cancer specifically.27,28
The disruptive effects of smoking on wound healing are likely associated with the need for unplanned reoperation, for which smoking also remained an independent risk factor following regression analysis. A breakdown of the 4 most common indications for reoperation in this cohort showed that compared with nonsmokers, smokers were significantly more likely to return to the operating room for repair of a disrupted wound. By contrast, there was no difference in the rates of reoperation required for surgical site infection or mechanical graft complications, including thromboembolism. This is notable because smoking is known to promote coagulation and has been shown to independently increase the risk of thromboembolic events.12,29 Furthermore, numerous studies have shown that preoperative tobacco use increases the chance of both superficial and deep incisional infections, neither of which were significantly elevated in smokers in the present study.14,30,31 Despite the increased need for unplanned reoperation in the smoking group, it is important to note that there was no difference in the rate of ultimate graft failure. Prior literature suggests that the majority of free flaps requiring surgical reexploration or operative repair can be salvaged, so reoperation may normalize flap failure rates between groups.9 However, any return to the operating room comes at significant cost and markedly prolongs length of hospital stay.32
Although our χ2 analysis results indicated that total surgical complications were significantly higher in smokers than in nonsmokers, this significance was lost following regression analysis, indicating that smoking status alone cannot account for this difference in surgical complications. In addition, there was no difference between groups in the rates of medical complications. These results stand in contrast to previous studies that have shown a significant association between smoking and postoperative pulmonary and neurological complications.4,30 In a recent study of patients undergoing laryngectomy, Brady et al33 also found no increase in overall morbidity attributable to smoking. These authors suggested that the prior literature may have failed to correct for the number of comorbidities associated with smoking, including differences in the extent of disease, which may artificially inflate the risk associated with tobacco smoke. Furthermore, it is possible that in extensive cancer resection procedures, such as free flap or laryngectomy, operative morbidity is largely a function of preoperative health status and the extent of disease rather than of individual risk factors such as tobacco use.
Additional insights can be gleaned from the stratification of smokers into groups based on the number of pack-years of smoking. As expected, the results of this analysis in the present study showed that patients with a longer history of smoking had significantly higher rates of numerous comorbidities. However, a longer history of smoking was not associated with increased medical, surgical or overall complications. This finding stands in contrast to prior studies that have shown a lifetime dose-related association of tobacco exposure with postoperative complications.14,34 For patients undergoing free flap surgery, these results may suggest that it is short-term exposure to smoke in the perioperative period rather than the quantity or duration of exposure that increases the risk of complications associated with wounds. While smoking is known to have both short- and long-term effects on normal physiology, there is evidence to suggest that cigarette smoke interferes with normal wound healing mechanisms in an acute manner.13 This is supported by studies of preoperative smoking cessation that have found that those who quit smoking 6 to 8 weeks prior to surgery have reduced wound-associated complications.35 In a study of patients undergoing head and neck surgery, those who achieved more than 3 smoke-free weeks preoperatively had significantly improved wound healing.36 Although further analysis specific to free flap repair is needed, these results reinforce the importance of smoking cessation counseling in the early workup of head and neck cancers.
Limitations
There are several notable limitations to our study, many of which are inherent to the use of a large national database. Although the NSQIP database identifies patients who have smoked in the last year, there is little information regarding patterns of smoking throughout the year or changes in smoking habits in the preoperative period. Furthermore, the database does not provide information specific to free flap procedures, such as donor site, number of anastomoses, flap monitoring, or reason for flap failure. These factors may alter patient outcomes but cannot be accounted for in this analysis. Similarly, NSQIP collects data for the 30 days following surgery but does not allow for assessment of long-term outcomes. Additional confounding from reporting errors cannot be excluded. Although the strength of the present analysis lies in the statistical power afforded by the NSQIP database, the results should be interpreted with these limitations in mind.
Conclusions
A significant proportion of patients undergoing free flap reconstruction of the head and neck are active smokers. Our results suggested that such patients faced significantly higher risk than nonsmokers of wound disruption and subsequent reoperation in the postoperative period. This increased risk held true even after consideration of the numerous comorbidities and advanced disease status associated with the smoking population. However, the risk of these postoperative complications appeared to be associated with recent smoke exposure rather than with lifetime dose because pack-years of smoking history did not significantly influence operative outcomes. Therefore, smoking cessation prior to free flap surgery of the head and neck may help to reduce the risk of wound-associated complications and the need for reoperation.
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