Major Lung Resection For Cancer Research Articles

180 - Review of the practices of post-operative analgesic prescription after major lung resection for cancer: single centre study

180 - Review of the practices of post-operative analgesic prescription after major lung resection for cancer: single centre study

Cold chain logistics: a possible mode of SARS-CoV-2 transmission?

<b>Objective:</b> To determine whether the improved outcome of a surgical procedure in high volume hospitals is specific to the volume of the same procedure. <b>Design and setting:</b> Analysis of secondary...

Three-incision robotic major lung resection for cancer.

BackgroundRegardless of the current trend in reduced port surgery, robotic surgery generally requires multiple (≥4) skin incisions for robotic arms and patient-side surgeons. In addition, the use of multiple arms results in interreference between the arms and the patient-side surgeon. In the current study, we reviewed our initial experience of a less invasive robotic approach for lung cancer.MethodsWe used 3 arms of the Da Vinci Xi system in an original manner: the camera was set at the most ventral arm for patients and the forceps for right and left hands were set at the more dorsal arms. We made a 4-cm incision in the eighth intercostal space along the middle-axillary line for the insertion of 2 ports for a camera and forceps. This window was eventually used for the extraction of the resected lobes. In addition, we made 1-cm incision along the posterior-axillary line for the remaining arm, and a 1.5-cm incision along the anterior-axillary line for a utility window for the patient-side surgeon.ResultsOur port setting contributed to preventing interference between the 2 adjacent arms (camera and forceps), as well as to improving the performance of the patient-side surgeon who does not experience interference from the robotic arms. During the initial experiences of 39 patients, the same procedure was successfully completed by 3 different console surgeons. There were no catastrophic events during the operations or in the 90-day postoperative period, although we experienced 2 open conversions (5%) for noncritical bleeding.ConclusionsWe established a 3-incision robotic surgery for lung cancer, which in addition to being patient-friendly, may facilitates collaboration between the console-surgeon and patient-side surgeon without compromising the performance of the console surgeon.

Les réadmissions après résection pulmonaire en France : la base de données du PMSI

Readmission within 30 days is an indicator of the quality of care, because it often reflects post-discharge care that is not optimal. The objective of this work is to measure over time on the one hand the readmission rate and on the other hand the number of hospitals with a standardized readmission rate beyond the national average. All patients with major pulmonary resection for lung cancer in France were extracted from the PMSI national database. Readmission within 30 days was defined as any new hospitalization either in the same hospital or in another establishment. From January 1, 2005 to December 31, 2018, 110,603 patients were included. The 30-day all-cause readmissions rate was 24.9% (n=27,540). Patients after pneumonectomy had a readmission rate of 37% (n=4918) and 23% after lobectomy (n=2684) (P<0.0001). For the first period, we counted 10 hospitals with a standardized readmissions rate above the 99.8 limit and 10 hospitals above the 95% limit. For the second period, 8 hospitals had a standardized readmission rate above the 99.8% limit and 11 hospitals above the 95% limit. For the third period, 7 hospitals had a standardized readmission rate above the 99.8% limit and 6 hospitals above the 95% limit. Readmissions to hospital 30 days after major lung resection for cancer in France declined little during these three periods. Measures to prevent readmissions should be introduced.

Double Blind Pilot Randomized Trial Comparing Extended Anticoagulation to Placebo Following Major Lung Resection for Cancer

Venous thromboembolism (VTE), which comprises pulmonary embolus (PE) and deep vein thrombosis (DVT), is a significant cause of postoperative morbidity and mortality. This pilot randomized control trial (RCT) evaluated the feasibility of a full-scale RCT investigating extended thromboprophylaxis in patients undergoing oncological lung resections. Patients undergoing oncological lung resections in 2 tertiary centers received in-hospital, thromboprophylaxis and were randomized to receive post-discharge low-molecular-weight heparin (LMWH) or placebo injections once-daily for 30 days. At 30 days postoperatively, all patients underwent chest computed tomography with PE protocol and bilateral leg venous ultrasound. Primary outcomes included feasibility and safety; VTE incidence and 90-day survival were secondary outcomes. Between December 2015 and June 2018, 619 patients were screened, of whom 62.7% (165/263) of eligible patients consented to participate, and 133 (81%) were randomized. One-hundred and 3 patients, (77.4%), completed the 90-day study follow-up. Reasons for non-participation pre-randomization included patient discomfort and LMWH/placebo administration challenges. Post-randomization withdrawals were due to patient preference, surgeon preference and minor adverse events. Six asymptomatic VTE events (5 PE and 1 DVT) were detected within 30 days (3 in each group), for an overall incidence of 7%. There were 3 minor and no major adverse events. This study is the first to demonstrate the feasibility and safety of a full-scale extended thromboprophylaxis RCT in thoracic surgical oncology. Our results demonstrate that, while recruitment and retention rates were modest, the study design is feasible and with minimal adverse events and no intervention-related mortality.

Safety and advantage of no drain policy after thoracoscopic major lung resection.

It is my great honor to express my opinion on the editorial commentary (1,2) regarding our paper, “No drain after thoracoscopic major lung resection for cancer helps preserve the physical function” (3). First of all, we could achieve a satisfactory outcome with our no drain strategy after major lung resection for cancer (4), partly because of comprehensive coverage by the national medical insurance system in Japan: most of the materials to seal air leaks, such as endostaplers, fibrin sealant, and bioabsorbable mesh, are covered by the Japanese national insurance system.

Serratus plane block for video-assisted thoracoscopic surgery major lung resection: a randomized controlled trial

The aim of this study was to evaluate the impact of 2 different analgesic approaches on pain, postoperative rehabilitation exercises and rescue analgesics of 2 groups of patients undergoing video-assisted thoracoscopic surgery (VATS) major lung resection for cancer. A total of 94 patients undergoing a VATS major lung resection were randomly allocated to 2 groups: the control group received intravenous and oral (i.e. systemic) analgesics while the intervention group received systemic analgesics plus pre-emptive serratus plane block. Pain perception was recorded until drainage removal or until 2 p.m. of postoperative day (POD) 3. In particular, the primary end point was defined as the peak pain perception on POD 1 (in the time frame between 6 a.m. and 2 p.m.). Secondary end points were the number of forced inspiration manoeuvers during rehabilitative incentive spirometry on POD 1 and 2 and the overall number of rescue analgesics requested by patients. Serratus plane block provided a better pain control between 6 a.m. and 2 p.m. of POD 1 (Numeric Rating Scale 1.7 vs 3.5; P < 0.001). Patients in the intervention group performed more forced inspiration manoeuvers at a mean higher volume during incentive spirometry (8.9 vs 7, P < 0.001, and 1010 vs 865 ml, P = 0.02). They required fewer rescue doses of analgesics (0.57 vs 1.1; P = 0.008). Serratus plane block provided a better pain control, entailing a better performance during postoperative rehabilitation exercises in terms of duration and quality of incentive spirometry. It diminished the patient's need for rescue analgesics during the early postoperative period. NCT03134729.

No Drain After Thoracoscopic Major Lung Resection for Cancer Helps Preserve the Physical Function

We previously proved that omitting chest tube drainage in select patients undergoing thoracoscopic major lung resection for cancer was safe. The aim of the present study was to clarify the impact of omitting postoperative chest tube drainage on preserving the early postoperative ventilatory capacity and exercise capacity. The subjects of this retrospective study were 116 patients undergoing either thoracoscopic radical segmentectomy (n= 18) or lobectomy (n= 98). Whether chest tube drainage was to be performed was determined from the predefined criteria. We routinely measured the vital capacity and 6-minute walking distance preoperatively, at postoperative day 1 and at postoperative day 7. Postoperative pain was assessed daily by the visual analogue scale, and the number of analgesic agents used until postoperative day 7 was recorded. Postoperative chest tube drainage was omitted in 53 patents (46%). Omitting chest tube drainage was associated with a substantial reduction in both the postoperative pain and the number of analgesic agents used on postoperative day 0 and 1. In addition, omitting chest tube drainage was associated with a preservation of vital capacity and the 6-minute walking capacity on postoperative day 1. The vital capacity, the 6-minute walking distance, and the pain as measured on postoperative day 1 were substantially correlated with each other. Omitting chest tube drainage results in reducing the pain, preservation of the ventilatory capacity, and preservation of exercise capacity in the early postoperative period in patients undergoing thoracoscopic major lung resection for cancer.

Size-capacity mismatch in the lung: a novel predictor for complications after lung cancer surgery

BackgroundThe aim of the present study was to make a combined pulmonary functional and anatomical assessment using spirometry and computed tomography (CT) to clarify the best predictor for cardiopulmonary complications after thoracoscopic major lung resection for cancer. MethodsWe retrospectively reviewed our prospective database of 304 patients undergoing thoracoscopic major lung resection for cancer. The total lung volume (TLV) was measured preoperatively using deep-inspiratory CT by summing the voxels representing −600 to −1024 Hounsfield units. Forced vital capacity (FVC) was measured by spirometry. FVC/TLV was used to diagnose a lung size-function mismatch. We compared among FVC/TLV, conventional spirometric parameters, and the risk of postoperative cardiopulmonary complications. ResultsPostoperative cardiopulmonary complications developed in 25 of 304 patients (8.2%). There were no cases of operative mortality. A stepwise logistic regression analysis revealed that a history of smoking and low FVC/TLV were independent risk factors for postoperative cardiopulmonary complications in various preoperative measurements. According to a receiver-operating characteristic analysis, FVC/TLV was the only variable that was statistically useful for predicting complications (area under the receiver-operating characteristic curve > 0.7). ConclusionsLung size-function mismatch was identified as the best predictor for cardiopulmonary complications after major lung resection for cancer among various spirometry- and CT-derived parameters. The usefulness of this parameter in screening for patients who are at risk of complications should be validated by a multicenter, large-scale study because it can be obtained through routine preoperative work.

Performance of wider parenchymal lung resection than preoperatively planned in patients with low preoperative lung function performance undergoing video-assisted thoracic surgery major lung resection.

Pulmonary assessment before major lung resections is used to determine patient's operability. In marginal cases, extensive pulmonary assessment is additionally important under the fear of a more radical parenchymal removal. This study investigates the outcome of wider lung parenchymal resections in patients with low lung functional status undergoing video-assisted thoracic surgery (VATS) major lung resection. The medical records of patients who underwent VATS major lung resection for cancer, over a period of 5 years (August 2009-August 2014), were retrospectively reviewed. Patients with postoperative forced expiratory volume in first second (ppoFEV1) or postoperative diffusional capacity for carbon monoxide (ppoDLCO) <40% who underwent wider lung resection than preoperatively planned (Group A) were compared with patients with ppoFEV1 or ppoDLCO <40% who underwent the planned operation (Group B) and patients with ppoFEV1 and ppoDLCO >40% who underwent wider resection than preoperatively planned (Group C). Data analysed included demographics, past medical history, the surgery planned and performed, the reason for higher parenchymal resection, the clinical and pathological stage, the length of stay (LOS), the morbidity, the 30-day mortality and the survival. Overall, 73 patients were analysed (15 patients in Group A, 50 patients in Group B and 8 patients in Group C). The mean age was 68.5 years and 31.5% were males. The wider lung resection regarded 7 patients who underwent bilobectomy instead of lobectomy and 16 patients who underwent pneumonectomy instead of lobectomy. The main reason for higher resection was the wider invasion of the mass (21 patients). The age, gender and body mass index between three groups were similar, whereas ppoFEV1 and ppoDLCO were different (P < 0.001 and P < 0.001 respectively). Conversions, pulmonary morbidity and the 30-day mortality between groups were similar (P = 0.67, P = 0.88 and P = 0.33, respectively). LOS between groups was not different (P = 0.46). Survival rate between groups was also similar (log-rank, P = 0.79). Wider lung parenchymal resection than preoperatively anticipated may be performed, even in patients with low lung functional status, without increased adverse outcome when compared with patients with good lung function. This finding indicates that the preoperative risk stratification based on lung function tests is questionable.

Prediction of postoperative dyspnea and chronic respiratory failure

BackgroundEven among patients considered to be functionally eligible for major lung resection, some experience postoperative dyspnea. Based on our previous study with quantitative computed tomography (CT), we hypothesized that postoperative dyspnea is associated with the collapse of the remaining lung, and thus, prediction of the postoperative lung volume may contribute to risk assessment for postoperative dyspnea. MethodsWe measured the emphysematous lung volume and functional lung volume (FLV) separately on whole lung CT using an image analysis software in 290 patients undergoing major lung resection for cancer between January 2006 and December 2012. The postoperative FLV was predicted by a stepwise multiple regression analysis. ResultsFourteen patients complained of postoperative dyspnea (complicated group), five of them presented with chronic respiratory failure. The postoperatively measured FLV was significantly lower in the complicated group than in the control group (P < 0.01). The postoperative FLV could be calculated using preoperative variables, including the forced vital capacity, number of resected segments, FLV, and emphysematous lung volume. The predicted postoperative FLV was significantly lower in the complicated group than in the control group (P < 0.01, area under the curve = 0.78; sensitivity 86%; specificity 73%). The predicted postoperative FLV was also useful in distinguishing complicated patients from matched-control patients who had similar preoperative pulmonary function (P = 0.02). ConclusionsPostoperative dyspnea is likely accompanied by a collapse of the remaining lung. Quantitative assessment of the lung morphology on preoperative CT is useful to screen for patients at risk of postoperative dyspnea.

Predicted postoperative lung function is associated with all-cause long-term mortality after major lung resection for cancer

Preoperative lung function is an independent predictor of long-term survival after lung resection for non-small-cell lung cancer (NSCLC). The extent of resection has an impact on operative mortality, determines postoperative lung function and may influence both overall- and cancer-specific survival. We sought to determine the impact of predicted postoperative (ppo) lung function on long-term survival after lung cancer resection. We previously reported long-term survival analyses for patients who underwent major lung resection for NSCLC 1980-2006. For this study, we calculated ppo spirometry (forced expiratory volume in the first second, FEV1) and diffusing capacity of the lung for carbon monoxide (DLCO) in the same cohort using the functional segment technique or quantitative perfusion scans when available, and updated survival data; missing data were imputed. We assessed the relationship of ppoFEV1 and ppoDLCO to long-term survival using Cox regression. Of 854 patients, 471 (55%) were men, the mean age was 63 years and median survival was 42 months. At the time of analysis, 70% of patients had died. On regression analysis, all-cause mortality was related to age, stage, performance status, renal function and prior myocardial infarction. Preoperative lung function was marginally associated with mortality [DLCO (10-percentage point decrease): HR (hazard ratio) 1.04, 95% confidence interval (95% CI) 1.00-1.08, P = 0.056; FEV1 (10-percentage point decrease): HR 1.04, 95% CI 1.00-1.09, P = 0.067]. In contrast, ppo lung function was strongly associated with mortality (ppoDLCO: HR 1.06, 95% CI 1.01-1.12, P = 0.024; ppoFEV1: HR 1.06, 95% CI 1.01-1.12, P = 0.031). Ppo lung function is strongly associated with long-term survival after major lung resection and is more strongly related to survival than preoperative lung function. Surgeons struggle with challenging decisions about the appropriate extent of resection for early-stage cancer, balancing factors such as operative morbidity/mortality, local recurrence and postoperative quality of life. Ppo lung function and its relation to survival also should be taken into consideration during such deliberations.

Verification of Early Removal of the Chest Tube after Absorbable Mesh‐based Pneumostasis Subsequent to Video‐assisted Major Lung Resection for Cancer

We previously reported that the combined use of absorbable mesh and fibrin glue is superior to the use of fibrin glue alone to stop intraoperative air leaks. However, concern remains about whether mesh-based pneumostasis can induce the recurrence of air leaks after chest tube removal. We reviewed our prospective database of selected patients (n = 206) who underwent video-assisted major lung resection for cancer. Exclusion criteria included simultaneous combined resection, induction radiotherapy, entire intrathoracic adhesion, or a history of prior ipsilateral thoracotomy. We sealed any intraoperative air leaks with absorbable mesh and fibrin glue and then carried out prophylactic chest-tube drainage for 1 day. Intraoperative air leaks were detected in 133 (65%) patients. Overall, air leaks were not detected postoperatively in 186 (91%) patients, allowing chest tube removal on the day after the operation. The mean length of time for chest tube drainage was 1.2 days. A prolonged air leak (>7 days) was observed in one (0.5%) patient, and this leak resolved by itself. After chest tube removal, an air leak recurred in six (2.9%) patients during the 30 day follow-up period, necessitating chest tube reinsertion. Although the recurrence was observed more frequently after segmentectomy than after lobectomy (p = 0.04), the recurrence was not observed more frequently in patients who had an intraoperative air leak than in patients who did not (p = 0.3). Early removal of the chest tube after pneumostasis with absorbable mesh is verified in selected patients who underwent video-assisted major lung resection for cancer. However, further attempts should be made to prevent air leaks after anatomical segmentectomy.

Diffusing capacity predicts long-term survival after lung resection for cancer

Predictors of long-term survival for patients with lung cancer assist in individualizing treatment recommendations. Diffusing capacity (DLCO) is a predictor of complications after resection for lung cancer. We sought to determine whether DLCO is also prognostic for long-term survival after lung resection for cancer. We assessed survival among patients in our prospective database who underwent lung resection for cancer between 1980-2006. Potential prognostic factors for all-cause mortality were evaluated by computing average annual hazard rates, and variables significantly associated with survival were included in multivariable Cox modelling. Multiple imputation was used to address missing values. Among 854 unique patients, there were 587 deaths. The median follow-up time from surgery was 9.6 years. Predictors of survival included age, stage, performance status, body mass index, history of myocardial infarction, renal function and DLCO. On univariate analysis, the hazard ratio increased incrementally compared with those with a DLCO of ≥ 80% (70-79%, 1.12; 60-69%, 1.29; <60%, 1.35). On multivariable analysis, DLCO was an independent predictor of long-term survival for all patients (corrected for all other important covariates; HR 1.04 per 10-point decrement; 95% CI 1.00-1.08; P = 0.05). Its prognostic ability for long-term survival was above and beyond its influence on operative mortality. DLCO is an independent and clinically important determinant of long-term survival after major lung resection for cancer, a finding that is not generally known. Knowledge of this may help improve selection of patients for lung resection and may help tailor the extent of resection, when possible, in order to appropriately balance operative risk with long-term outcomes.

Sutureless pneumostasis using bioabsorbable mesh and glue during major lung resection for cancer: Who are the best candidates?

Sutureless pneumostasis using bioabsorbable mesh and glue during major lung resection for cancer: Who are the best candidates?

Mesh-Based Pneumostasis Contributes to Preserving Gas Exchange Capacity and Promoting Rehabilitation After Lung Resection

We recently introduced a technique of sutureless, mesh-based pneumostasis for preventing alveolar air leaks after lung resection. To verify the clinical usefulness of this technique, we examined if it can contribute to preserving gas exchange capacity and promoting postoperative rehabilitation. We prospectively collected perioperative data, including arterial oxygen saturation on postoperative day (POD) 1 and the length of postoperative rehabilitation in 100 patients undergoing elective, video-assisted major lung resection for cancer. Before April, 2006, intraoperative air leaks were sealed with the conventional method (control group), and thereafter, with bioabsorbable mesh and glue, without suturing, (treated group). To reduce the bias in comparison of the nonrandomized control group, we paired the treated group with the control group using the nearest available matching method on the estimated propensity score. Thirty-five patients in the control group were matched to 35 patients in the treated group based on the estimated propensity score. The length of both chest tube drainage and postoperative rehabilitation were significantly shorter in the treated group than in the control group (median, 1 versus 1 d, P = 0.03; 2 versus 3 d, P = 0.01, respectively). The arterial oxygen saturation on POD 1 was significantly higher in the treated group than in the control group (median, 94.0 versus 92.5 %, P = 0.03). Mesh-based pneumostasis during video-assisted major lung resection enabled early chest tube removal, preserved postoperative oxygenation capacity, and promoted postoperative rehabilitation, which may facilitate fast-track surgery for patients undergoing video-assisted major lung resection for cancer.

Sutureless pneumostasis using bioabsorbable mesh and glue during major lung resection for cancer: Who are the best candidates?

Preventing air leaks after major lung resection for cancer is mandatory for successful fast-track surgical intervention. We reported our preliminary results with performance of pneumostasis by combining polyglycolic acid mesh and fibrin glue; however, the advantages of this combination over the conventional method have not been clarified. We controlled air leaks detected during an intraoperative water-seal test by using sutures and fibrin glue before April 2006 and by combining polyglycolic acid mesh and fibrin glue without sutures thereafter. We removed the chest tube the day after the air leaks stopped. For bias reduction in comparison with the 2 historical cohorts, we used the nearest available matching method with the estimated propensity score. The durations of chest tube drainage and postoperative hospital stay were significantly shorter in the mesh-and-glue group (n = 61) than in the glue-alone group (n = 61). The incidence of postoperative pulmonary complications was lower in the mesh-and-glue group than in the glue-alone group (0% vs 7%, P = .042). According to a stratification analysis, the benefit of combining mesh and glue to reduce the duration of chest tube drainage was limited in patients undergoing upper lobe resection and in patients with severe emphysema undergoing other types of resection. Combining bioabsorbable mesh and glue for pneumostasis can reduce the duration of chest tube drainage, postoperative hospital stay, and pulmonary complications after major lung resection for cancer. Patients undergoing upper lobe resection and those with severe emphysema might be the best candidates for this technique.

Impact of Video-Assisted Thoracoscopic Major Lung Resection on Immune Function

Video-assisted thoracoscopic major lung resection for early stage non-small-cell lung carcinoma has been associated with less postoperative pain, better preserved pulmonary function, shorter hospital stay, and enhanced tolerance of adjuvant chemotherapy compared to thoracotomy. Initial concerns regarding safety, oncological clearance, and cost effectiveness were unfounded. Several recent trials have reported improved long-term survival in patients with early stage non-small-cell lung carcinoma undergoing video-assisted thoracoscopic major lung resection, compared to the open technique, although there are inconsistencies. Interestingly, the immune status and autologous tumor killing ability of lung cancer patients have previously been associated with long-term survival. Video-assisted thoracoscopic lung resection results in an attenuated postoperative inflammatory response, but more importantly, it better preserves postoperative immune function. Circulating natural killer and T-cell numbers, T-cell oxidative activity, and levels of immunochemokines such as insulin growth factor binding protein-3 are higher after video-assisted thoracoscopic surgery than after thoracotomy. Recently, interest has developed in the role of the angiogenesis factor, vascular endothelial growth factor, after cancer surgery. Whether differences in immunological and biochemical mediators contribute towards improved long-term survival following video-assisted thoracoscopic major lung resection for cancer remains to be confirmed.

Quantitative Computed Tomography Versus Spirometry in Predicting Air Leak Duration After Major Lung Resection for Cancer

Emphysema is a well-known risk factor for developing air leak or persistent air leak after pulmonary resection. Although quantitative computed tomography (CT) and spirometry are used to diagnose emphysema, it remains controversial whether these tests are predictive of the duration of postoperative air leak. Sixty-two consecutive patients who were scheduled to undergo major lung resection for cancer were enrolled in this prospective study to define the best predictor of postoperative air leak duration. Preoperative factors analyzed included spirometric variables and area of emphysema (proportion of the low-attenuation area) that was quantified in a three-dimensional CT lung model. Chest tubes were removed the day after disappearance of the air leak, regardless of pleural drainage. Univariate and multivariate proportional hazards analyses were used to determine the influence of preoperative factors on chest tube time (air leak duration). By univariate analysis, site of resection (upper, lower), forced expiratory volume in 1 second, predicted postoperative forced expiratory volume in 1 second, and area of emphysema (< 1%, 1% to 10%, > 10%) were significant predictors of air leak duration. By multivariate analysis, site of resection and area of emphysema were the best independent determinants of air leak duration. The results were similar for patients with a smoking history (n = 40), but neither forced expiratory volume in 1 second nor predicted postoperative forced expiratory volume in 1 second were predictive of air leak duration. Quantitative CT is superior to spirometry in predicting air leak duration after major lung resection for cancer. Quantitative CT may aid in the identification of patients, particularly among those with a smoking history, requiring additional preventive procedures against air leak.

Conventional models overestimate the statistical significance of volume–outcome associations, compared with multilevel models

Objective To compare the use of conventional statistical models with multilevel regression models in volume–outcome analyses of surgical procedures in an empirical case study. Study Design and Setting Using conventional regression models and multilevel regression models, we estimated the effect of hospital volume and surgeon volume on 30-day mortality and length of postoperative hospital stay in persons who had an esophagectomy, pancreaticoduodenectomy, or major lung resection for cancer in Ontario, Canada, from 1994 to 1999. Results The point estimates of volume–outcome associations were similar using either method; however, the 95% confidence intervals estimated by multilevel models were wider than those estimated by conventional models. A significant association between volume and mortality was identified in 2 of 18 (11%) comparisons using conventional analysis but in none of the 18 (0%) comparisons using multilevel analysis, and between volume and length of stay in 15 of 18 (83%) comparisons using conventional analysis and in 1 of 18 (6%) comparisons using multilevel analysis. Conclusion Conventional and multilevel statistical models can yield substantially different results in the analysis of volume–outcome associations for surgical procedures.