Abstract
Introduction
Elective surgeries of the upper extremity are generally considered safe procedures with good outcomes and relatively low rates of postoperative complications.1-6 However, given the large volume of elective upper extremity surgeries performed in the United States annually, complications do exist. These postoperative complications can be the source of significant patient morbidity.1,3,4,6,7 Therefore, surgeons are responsible for recognizing and treating modifiable risk factors that influence the rates of complications after elective upper extremity surgery.
Smoking has been well established as a modifiable risk factor for complications across various orthopedic procedures, including primary and revision total hip and knee arthroplasty, total shoulder arthroplasty, lumbar spine surgery, and ankle fracture fixation.8-14 Cigarette smoking induces a host of negative physiological effects on the upper extremity and digits, including peripheral vasoconstriction, decreased oxygenation, and alterations in the collagen formation and coagulation cascade.15,16 Taken together, these can have a detrimental effect on wound healing.
Despite the well-studied effects of smoking on numerous orthopedic procedures, there is a paucity of literature examining the influence of smoking on elective upper extremity surgery. Given the breadth and frequency of elective upper extremity surgery procedures, it is imperative to understand the potential deleterious effects of smoking in this setting, especially considering that this may represent a potentially modifiable risk factor. Such an understanding would allow for improved preoperative decision-making and patient counseling. Therefore, the purpose of this study was to explore the impact of smoking on short-term complications, readmissions, and reoperations after elective upper extremity surgery using a large multicenter national database. We hypothesized that smokers will have an increased rate of complications, readmissions, and reoperations compared with a cohort of nonsmokers undergoing elective upper extremity surgery.
Methods
This study received exemption from the institutional review board given the deidentified nature of the information collected. The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) collects patient demographics, comorbidities, perioperative variables, and 30-day postoperative data from more than 600 public and private surgical sites nationwide. Trained clinical reviewers prospectively review medical records and compile this information into the NSQIP database. This database is internally audited for accuracy and has been shown to be reliable.17,18
In this study, all patients undergoing elective upper extremity surgery from 2012 to 2017 were identified in the ACS NSQIP registry using Current Procedural Terminology (CPT) codes. A complete list of all 338 CPT codes can be seen in Appendix A. Patients were excluded from analysis if they were older than 90 years of age, underwent nonelective surgery (eg, coded as urgent or emergent), or had incomplete records. The 15 most common soft-tissue and bony CPT codes included in this study are depicted in Table 1. The data collected were divided into patient demographics, comorbidities, perioperative variables, and outcomes. Patient demographics collected for analysis included age, sex, and body mass index (BMI). Specific comorbidity data collected included steroid use, diabetes mellitus, hypertension, impaired coagulation, dyspnea, congestive heart failure, dialysis, and chronic obstructive pulmonary disease. Perioperative variables were collected and reviewed, including preoperative functional status, American Society of Anesthesiologists (ASA) classification, and surgical setting (inpatient vs outpatient). In addition, the included CPT codes were divided into primary bone and joint procedures versus soft-tissue-based procedures by the senior author to assess the impact of smoking on these 2 subcohorts.
Included Primary CPT Surgical Procedure Codes of Elective Upper Extremity Surgery.
Note. CPT = Current Procedural Terminology.
Primary 30-day postoperative outcomes reviewed included superficial and deep surgical site infections (SSIs), wound dehiscence, reoperations, and readmissions. Trained practitioners, following the NSQIP user guide, evaluated superficial and deep SSIs and wound dehiscence. 18 Surgical site infections were defined according to the Centers for Disease Control and Prevention criteria. In brief, superficial site infections involve the skin or subcutaneous tissues of the surgical site, and deep SSIs involve the deep spaces or organs of the surgical site. 19 The NSQIP defines readmissions and reoperations as an unplanned readmission or reoperation within 30 days and likely related to the original surgical procedure. Further details regarding the comprehensive methodology used to collect the aforementioned information can be found in the NSQIP User Guide. 18
Smoking status was collected through chart review, and patients were grouped into 2 cohorts: current smokers and nonsmokers. The ACS NSQIP defines current smokers as any patient who had reported smoking cigarettes within the year prior to surgery. Nonsmokers are defined as those who had not smoked cigarettes within the year prior to surgery. These 2 cohorts, current smokers and nonsmokers, were compared regarding patient demographics, comorbidities, and perioperative variables. In addition, postoperative outcomes including complications, readmissions, and reoperations were compared between the 2 groups.
Descriptive statistics of patient factors were reported using mean and standard deviation. Comparisons between patients who reported current and noncurrent smoking were performed using Student t test or Mann-Whitney U test for continuous variables when appropriate, as well as χ2 test of independence or Fisher exact test for categorical variables. Subsequent P values were adjusted using Benjamini-Hochberg false discovery rate to account for increased type I error rate due to multiple comparisons.
Multivariate logistic regression was used to identify statistically independent patient factors associated with postoperative outcomes of interest. To avoid overadjustment through inclusion of all patient variables, factors were selected using forward and backward stepwise regression. Selected variables were also assessed for significant collinearity using variance inflation factor (VIF) analysis. A VIF value of 5.0 was used as the threshold to signify significant collinearity. To calculate adjusted odds ratios (aORs), continuous variables such as age were converted to binary categorical variables by determining statistical cutoffs using receiver operating characteristic curve analysis. An α value of 0.05 was used to denote statistical significance. All analyses were performed using the open-source statistical programming software, R version 3.5.1 (R Foundation for Statistical Computing, Vienna, Austria).
Results
A total of 107 943 patients were identified, using the aforementioned CPT codes, as having undergone elective upper extremity surgery from the years 2012 to 2017. After exclusion, 73 806 patients were available for review. Of these, 15 820 (21.4%) were current smokers in the year prior to surgery, and 57 986 (78.6%) were nonsmokers.
Smokers were noted to be significantly younger (P < .001), more often men (P < .001), and with a lower BMI (P < .001). Regarding comorbidities, smokers were noted to have lower rates of steroid use (P < .001), diabetes mellitus (P < .001), hypertension (P < .001), impaired coagulation (P < .001), and dialysis use (P < .001). However, current smokers were noted to have higher rates of dyspnea (P < .001) and chronic obstructive pulmonary disease (P < .001). Upon review of perioperative variables, smokers were less likely to have an independent preoperative functional status (P = .005) and more likely to undergo a procedure classified as bony compared with nonsmokers (P < 0.001). No difference was found between ASA classification (P = .991) and surgical setting (P = .957) between the 2 groups (Table 2)
Patient Demographics and Factors of Current Smokers and Noncurrent Smokers Undergoing Elective Upper Extremity Surgery.
Note. SD = standard deviation; BMI = body mass index; ASA = American Society of Anesthesiologists.
Determined through pairwise t tests, post hoc Tukey Honestly Significant Difference test, multiple χ2 or Fisher exact test after initial analysis of variance, Kruskal-Wallis test, or χ2 test of independence or Fisher exact test. P values were adjusted using the false discovery rate P value adjustment for multiple comparisons. Significant P values are in bold.
In the univariate analysis, current smoking was associated with a significantly higher rate of superficial and deep SSIs (P < .001) and a significantly higher rate of wound dehiscence (P = .004). In addition, current smoking was associated with a significantly higher readmission (P = .003) and reoperation rate (P < .001) (Table 2).
In the multivariate analysis performed to control for cofounding variables, current smoking was significantly associated with overall surgical site complications (aOR, 1.62; 95% confidence interval [CI], 1.39-1.89), superficial SSIs (aOR, 1.51; 95% CI, 1.22-1.85), and deep SSIs (aOR, 1.73; 95% CI, 1.34-2.22). In addition, current smoking was significantly associated with reoperation (aOR, 1.50; 95% CI, 1.24-1.80) and readmission (aOR, 1.49; 95% CI, 1.23-1.80). Furthermore, the presence of chronic obstructive pulmonary disease was also associated with 67% increased odds of readmission (aOR, 1.67; 95% CI, 1.19-2.29). Additional significant risk factors for surgical site complications, readmission, and reoperation are listed in Table 3.
Adjusted Odds Ratios for Various Postoperative Complications Up To 30 Days After Elective Surgery of the Upper Extremity.
Note. SSI = surgical site infection; aOR = adjusted odds ratio; CI = confidence interval; ASA = American Society of Anesthesiologists.
aORs determined using coefficients determined through multivariate logistic regression. Factors were selected for inclusion in the model using stepwise regression with forward and backward selection. Significant ratios are in bold.
Cutoff values for age and surgery duration were determined using receiver operative characteristic analysis.
Defined as smoking within 1 year prior to surgery.
Discussion
Given the nature of elective upper extremity surgery, physicians must preoperatively identify all modifiable risk factors in efforts to reduce complications. Smoking has been identified as a modifiable risk factor for postoperative complications after various orthopedic surgeries.8-14 The influence of smoking on outcomes after elective upper extremity surgery, however, is less defined. Therefore, this study set out to evaluate the impact of smoking on complications, readmissions, and reoperations after elective upper extremity surgery using a large national database. This study demonstrates that current smokers have a significantly higher rate of complications, readmissions, and reoperations after elective upper extremity surgery when controlling for baseline patient and surgical characteristics.
There are few studies that have looked at the influence of smoking on surgical site complications after upper extremity surgery. Hustedt et al reviewed 49 272 patients and developed a risk stratification tool for complications after hand surgery. The authors identified tobacco abuse as a significant independent predictor of postoperative complications. 2 Werner et al, 1 in a review of 454 987 patients, identified tobacco use as a significant independent risk factor for infection after open carpal tunnel release. Bykowski et al 6 found that smoking was associated with SSIs in a review of 8850 patients undergoing outpatient elective hand surgery at a single center. In contrast to the aforementioned studies, Lipira et al 4 reviewed the NSQIP data from 2006 to 2011 and found in their multivariate analysis that current smoking was not independently associated with 30-day complications after hand surgery.
The association between smoking and complications after orthopedic procedures based outside the upper extremity, however, has been well established in the literature. Sahota et al 8 published a propensity score–matched analysis in 2018 that found that smokers were nearly twice as likely to have a surgical complication after total knee or total hip arthroplasty. In an institutional review in 2017, Hatta et al 11 found that patients with a smoking history had a 5 times greater risk of periprosthetic infections after total shoulder arthroplasty. In an NSQIP review of 8776 patients undergoing revision total knee arthroplasty, Bedard et al 10 found that smokers had a significantly increased risk of wound complications. In a similar study, Bedard et al 9 found an increased risk of deep wound infection when comparing smokers and nonsmokers undergoing revision total hip arthroplasty. In another study of 35 477 patients undergoing lumbar spine surgery, Martin et al 12 found a significantly higher rate of wound complications when comparing current smokers with patients without a smoking history. The results from this study are concordant with the published results having identified current smoking as an independent risk factor for postoperative complications for patients undergoing elective upper extremity surgery.
The association between smoking and surgical site complications is hypothesized to be secondary to the negative physiological effects of smoking on perfusion. Nicotine, absorbed through smoking, stimulates the release of catecholamines and has been shown to induce peripheral vasoconstriction and decrease blood flow.15,16 This was seen in a recent study assessing the influence of nicotine on hand microcirculation. Pywell et al 15 found that nicotine (24 mg) e-cigarettes led to a significant reduction in hand microcirculation in smokers for up to 20 minutes after use. In addition, Morecraft et al 20 studied the hemodynamic effects of smoking on digital arteries and found a 60% decrease in arterial blood flow in the first measurement taken after smoking. Along with decreased blood flow, smoking can lead to decreased oxygenation of peripheral tissues. The carbon monoxide produced from cigarette smoke displaces oxygen from hemoglobin, decreasing local tissue oxygenation.15,16 In addition, smoking alters the production of local tissue factors contributing to a hypercoagulable state and decreased collagen formation, negatively influencing wound healing. 16 In combination, these local and systemic effects of smoking can translate into adverse patient outcomes and surgical site complications that may necessitate further patient care.
In addition to the increased risk of complications with smoking, the present investigation also identified that current smokers had a significantly higher rate of readmissions and reoperations. Other literature works have similarly explored this association. Sahota et al, 8 in an analysis of 1251 smokers matched to nonsmokers, found that smokers were more than 3 times more likely to have a readmission and almost 2 times more likely to have a reoperation after total hip or knee arthroplasty. Bedard et al 9 found in their multivariate analysis that smokers had a significantly higher risk of reoperation compared with nonsmokers undergoing revision total hip arthroplasty. Hess et al 7 found that smokers had a higher rate of revision procedures in their multivariate regression analysis comparing distal radius fracture fixation in smokers and nonsmokers. Despite the low overall complication rate of elective upper extremity surgery, readmissions and reoperations cause additional patient morbidity and financial costs. Therefore, surgeons are responsible for understanding all risk factors of readmissions and reoperations.
Surgeons and clinicians should make all efforts to mitigate these increased risks of complications, readmissions, and reoperations seen in smokers. Perhaps the most important way to decrease these risks is through a period of smoking cessation prior to surgical intervention. Unfortunately, limited evidence exists assessing the influence of smoking cessation on postoperative complications. A randomized controlled trial by Lindstrom et al in 2008 attempted to understand the association of smoking cessation and complications after orthopedic and general surgery procedures. In this study, patients in the smoking cessation group received both counseling and nicotine substitution from 4 weeks preoperatively to 4 weeks postoperatively. The authors found that the smoking cessation cohort had reduced rates of postoperative complications. 21 A review article on smoking and hand surgery by Wei and Strauch 16 concluded similar findings and advocated for at least 4 weeks of smoking cessation to improve outcomes. Until more concrete evidence has been established regarding elective upper extremity procedures, surgeons should encourage smoking cessation for a minimum of 4 weeks prior to surgical intervention.
The strengths of this study include the large patient population, the wide range of perioperative variables collected, and the audited nature of the NSQIP data collection. In addition, a multivariate regression model was used to control for differences in patient demographics and comorbidities between the 2 cohorts. Despite these strengths, our study has several limitations to address. First, the data analysis was limited to the variables that were collected by NSQIP, including the collection of complications only within the first 30 days. Many orthopedic-specific outcomes and complications were therefore not collected, including functional outcomes, range of motion, delayed union, malunion, nonunion, and chronic regional pain syndrome. Conceptually, it may be hypothesized that active smokers would demonstrate a higher incidence of delayed union and nonunion; however, this cannot be assessed as a limitation of the current database. Second, although NSQIP has been shown to be reliable with internal quality control assessments, large databases are subject to potential coding inaccuracies. In addition, there are a number of common elective upper extremity procedures, including carpal tunnel release, cubital tunnel decompression, trigger digit release, and select small joint fusions, that are not captured within the NSQIP database (unless bundled with a separate primary procedure code). Nevertheless, the available cohort of elective upper extremity surgery includes significant breadth with respect to the procedural complexity and the primary tissue addressed (bone and joint vs soft tissue), allowing for meaningful comparisons between the 2 cohorts.
There is also an important limitation regarding the definition of smoking in this study. The NSQIP defines current smoking as smoking within 1 year of surgery, and therefore our study was not able to distinguish between current daily smokers and those who have quit within the last year. Another limitation is the lack of pack-year data in our analysis that precludes any understanding of the impact of the quantity of smoking on outcomes. Furthermore, smoking status was self-reported by patients and therefore may be underreported in this study. Finally, NSQIP does not collect data on chewing tobacco, cigars, e-cigarettes, or other forms of tobacco that might influence our outcomes.
In conclusion, current smoking was found to be significantly associated with an increase in surgical site complications, readmissions, and reoperations after elective upper extremity surgery. Surgeons should consider smoking a modifiable risk factor for postoperative complications and appropriately counsel patients on outcomes and complications given the elective nature of these interventions. Future research should be directed toward understanding the influence of smoking cessation prior to surgery.
Footnotes
Appendix
CPT Codes for Elective Procedures of the Upper Extremity.
| CPT | CPT | CPT | CPT | CPT | CPT | CPT | CPT |
|---|---|---|---|---|---|---|---|
| 20816 | 24361 | 25111 | 25390 | 25825 | 26410 | 26540 | 26862 |
| 20822 | 24362 | 25112 | 25391 | 25830 | 26412 | 26541 | 26863 |
| 20827 | 24363 | 25115 | 25392 | 25900 | 26415 | 26542 | 26910 |
| 24000 | 24365 | 25116 | 25393 | 25905 | 26416 | 26545 | 26951 |
| 24006 | 24366 | 25118 | 25400 | 25907 | 26418 | 26546 | 26952 |
| 24075 | 24495 | 25119 | 25405 | 25909 | 26420 | 26548 | 26989 |
| 24076 | 24515 | 25120 | 25415 | 25920 | 26426 | 26550 | 29840 |
| 24077 | 24516 | 25125 | 25420 | 25927 | 26428 | 26555 | 29844 |
| 24101 | 24538 | 25126 | 25425 | 25929 | 26433 | 26560 | 29845 |
| 24102 | 24545 | 25130 | 25426 | 25931 | 26434 | 26561 | 29846 |
| 24105 | 24546 | 25135 | 25430 | 25999 | 26437 | 26562 | 29847 |
| 24110 | 24566 | 25136 | 25431 | 26045 | 26440 | 26565 | 29848 |
| 24115 | 24575 | 25145 | 25440 | 26055 | 26442 | 26567 | 35045 |
| 24116 | 24579 | 25150 | 25441 | 26116 | 26445 | 26568 | 35206 |
| 24120 | 24582 | 25151 | 25442 | 26117 | 26449 | 26580 | 35207 |
| 24125 | 24586 | 25170 | 25443 | 26121 | 26450 | 26587 | 35236 |
| 24126 | 24587 | 25210 | 25444 | 26123 | 26455 | 26590 | 35266 |
| 24130 | 24615 | 25215 | 25445 | 26125 | 26460 | 26591 | 64718 |
| 24134 | 24635 | 25230 | 25446 | 26130 | 26471 | 26593 | 64719 |
| 24138 | 24665 | 25240 | 25447 | 26135 | 26474 | 26596 | 64721 |
| 24140 | 24666 | 25248 | 25449 | 26140 | 26476 | 26608 | 64821 |
| 24145 | 24685 | 25260 | 25490 | 26145 | 26477 | 26615 | 64822 |
| 24147 | 24800 | 25263 | 25491 | 26160 | 26478 | 26650 | 64823 |
| 24149 | 24802 | 25265 | 25492 | 26170 | 26479 | 26665 | |
| 24150 | 24900 | 25270 | 25515 | 26180 | 26480 | 26676 | |
| 24152 | 24925 | 25272 | 25525 | 26185 | 26483 | 26685 | |
| 24155 | 24930 | 25274 | 25526 | 26200 | 26485 | 26686 | |
| 24201 | 24999 | 25275 | 25545 | 26205 | 26489 | 26706 | |
| 24301 | 25000 | 25280 | 25574 | 26210 | 26490 | 26715 | |
| 24305 | 25001 | 25290 | 25575 | 26215 | 26492 | 26727 | |
| 24310 | 25020 | 25295 | 25606 | 26230 | 26494 | 26735 | |
| 24320 | 25023 | 25300 | 25607 | 26235 | 26496 | 26746 | |
| 24330 | 25024 | 25301 | 25608 | 26236 | 26497 | 26756 | |
| 24331 | 25025 | 25310 | 25609 | 26250 | 26498 | 26765 | |
| 24332 | 25035 | 25312 | 25628 | 26260 | 26499 | 26776 | |
| 24340 | 25040 | 25315 | 25645 | 26350 | 26500 | 26785 | |
| 24341 | 25075 | 25316 | 25652 | 26352 | 26502 | 26820 | |
| 24342 | 25076 | 25320 | 25670 | 26356 | 26508 | 26841 | |
| 24343 | 25077 | 25332 | 25676 | 26357 | 26510 | 26842 | |
| 24344 | 25085 | 25337 | 25685 | 26358 | 26520 | 26843 | |
| 24345 | 25101 | 25350 | 25695 | 26370 | 26525 | 26844 | |
| 24346 | 25105 | 25355 | 25800 | 26372 | 26530 | 26850 | |
| 24358 | 25107 | 25360 | 25805 | 26373 | 26531 | 26852 | |
| 24359 | 25109 | 25365 | 25810 | 26390 | 26535 | 26860 | |
| 24360 | 25110 | 25375 | 25820 | 26392 | 26536 | 26861 |
Note. CPT = Current Procedural Terminology.
Ethical Approval
This study was approved by our institutional review board.
Statement of Human and Animal Rights
This article does not contain any studies with human or animal subjects.
Statement of Informed Consent
No identifying patient details were provided in this manuscript, and therefore informed consent was not obtained.
Declaration of Conflicting Interests
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: D.S. is a consultant and speaker for Endo Pharmaceuticals. The rest of the authors declare that they have no conflicts of interest to declare.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
