Abstract
Purpose
With enhancements in patient safety and improvements in anesthesia administration, outpatient thyroidectomy is now frequently undertaken as an outpatient procedure, with several peer-reviewed reports of safe implementation totaling over 4500 procedures since 2006. However, robust statistical analyses of predictors for readmission are lacking.
Methods
The 2011 NSQIP data set was queried to identify all patients undergoing thyroidectomy on an outpatient basis. Outcomes of interest included surgical and medical complications, reoperation, mortality, and readmission. Univariate and multivariate analyses were utilized to identify the predictors of these events.
Results
In total 5121 patients were identified to have undergone an outpatient thyroidectomy in 2011. Overall 30-day morbidity was rare with only 47 patients (0.92%) experiencing any perioperative morbidity. One hundred eleven (2.17%) patients were readmitted within 30 days of the operation. A history of COPD was the only preoperative comorbid medical condition that significantly increased a patient’s risk for readmission (OR 3.73 95% CI 1.57–8.85, p = 0.003). Patients with a surgical complication were more than 7 times as likely to be readmitted (OR 2.08–25.28, p = 0.002), and those with a medical complication were over 19 times as likely to be readmitted (OR 7.32–50.78, p < 0.001).
Conclusions
Readmission after outpatient thyroidectomy is infrequent, and compares well with other outpatient procedures. The main identified risks include preoperative COPD and any of the generic postoperative complications tracked in NSQIP. As procedures continue to transition into outpatient settings and financial penalties associated with readmission become a reality, these findings will serve to optimize outpatient surgery utilization.
1
Introduction
With enhancements in patient safety and improvements in anesthesia administration, outpatient surgery has evolved into a safe option for many patients. In keeping with this trend, thyroidectomy is now frequently undertaken as an outpatient procedure, with several peer-reviewed reports of safe implementation totaling over 4500 procedures since 2006 . The American Thyroid Association recently commissioned an interdisciplinary Task Force to develop a consensus statement to help define the eligibility criteria for outpatient thyroidectomy . However, debate surrounds the routine use of outpatient thyroidectomy.
Hospital readmission has been under scrutiny for many years for its contribution to higher medical bills and increased healthcare costs . It has also garnered attention for its use as a metric of healthcare quality and subsequent relation to medical reimbursement. Most recently, the current administration instituted its Hospital Readmissions Reduction Program (HRRP) through the Patient Protection and Affordable Care Act, which has established penalties for hospitals that display above average hospital readmission rates . Such penalties can deduct up to 1% of the total Medicare reimbursement for an affected hospital . While the statute presently applies to a limited number of conditions, the Centers of Medicare and Medicaid Services plan to expand the set of applicable conditions in 2015 . The utility of readmission data extends to prevention measures: it could be used to assess risk factors for readmission. However, this requires the ability to develop accurate methods to identify high-risk patients. While existing studies on outpatient thyroidectomy are useful, they are largely limited to single-center, single surgeon experiences. Similarly, the predictive power of currently available readmission models is generally poor .
NSQIP began capturing 30-day readmission data in January 2011, including planned readmissions, unplanned readmissions (UR), and suspected causes for readmission. NSQIP is a nationally validated, risk-adjusted surgical outcomes database, aimed at measuring and improving the quality of care delivered to surgical patients. The database provides a robust cohort of patients from which a high-powered retrospective study can be performed, and it continues to be used to identify relevant clinical elements in various specialties. Recently, Mlodinow et al. and Kim et al. . published their findings using the NSQIP database. The change to outpatient thyroidectomy has occurred in the absence of data for defining the eligible population of patients or uniformly endorsed precautions for pursuing an outpatient approach. This study aims to identify predictors of 30-day unplanned readmission after outpatient thyroidectomy, using the NSQIP database.
2
Methods
2.1
Data acquisition and patient selection
The American College of Surgeons NSQIP registry is a validated, national surgical outcomes database, aimed at measuring and improving upon the quality of care delivered to surgical patients across the United States. Data collection methods for the NSQIP registry have been previously described in detail . In brief, these data are independently abstracted by trained surgical nurses and are subject to random audits providing a high quality, standardized database that has a demonstrated disagreement rate of less than 1.8%. The NSQIP database was retrospectively queried for data on all patients undergoing an outpatient thyroidectomy in 2011 at over 350 participating institutions.
Patients undergoing thyroidectomy were identified using the Current Procedural Terminology codes 60220, 60225, 60240, 60252, 60254, 60270, and 60271 ( Table 1 ). Outpatient procedures were identified by the inpatient/outpatient variable in the NSQIP registry. Of note, outpatient surgery is defined as one requiring less than 23 hours stay in hospital.
| 60220 | Total thyroid lobectomy, unilateral; with or without isthmusectomy |
| 60225 | Total thyroid lobectomy, unilateral; with contralateral subtotal lobectomy, including isthmusectomy |
| 60240 | Thyroidectomy, total or complete |
| 60252 | Thyroidectomy, total or subtotal for malignancy; with limited neck dissection |
| 60254 | Thyroidectomy, total or subtotal for malignancy; with radical neck dissection |
| 60270 | Thyroidectomy, including substernal thyroid; sternal split or transthoracic approach |
| 60271 | Thyroidectomy, including substernal thyroid; cervical approach |
2.2
Outcomes and risk adjustment variables
The primary outcomes of interest were unplanned 30-day hospital readmission and 30-day reoperation. Readmissions included hospitalization to either the same or another hospital after the initial surgical procedure. Hospitalizations within 30 days of discharge that were planned at the time of surgery were not included. The ACS-NSQIP participant use file’s readmission data has been previously validated and shown to accurately capture unplanned readmission events . Reoperation was defined as an unplanned return to the operating room for a surgical procedure related to either the index or a concurrent procedure.
Secondary outcomes of interest were overall morbidity, surgical complications, overall medical complication, and death within 30 days of the operation. Overall 30-day morbidity was defined as the presence of one or more perioperative surgical or medical complications. Surgical complications included superficial, deep, and organ/space surgical site infections (SSI) and wound dehiscence. Medical complications included deep vein thrombosis, pulmonary embolism, ventilator dependence for > 48 hours, unplanned re-intubation, pneumonia, renal insufficiency, acute renal failure, urinary tract infection, coma, stroke, peripheral nerve injury, cardiac arrest, myocardial infarction, bleeding requiring transfusion, and sepsis or septic shock. Reoperation was defined as an unplanned return to the operating room for a surgical procedure related to either the index or a concurrent procedure.
Preoperative variables collected by NSQIP include demographic data, medical comorbidities, operative time, and concurrent surgical procedures. Patient demographics collected include age, body-mass index (BMI), race, gender, active smoking status, steroid use, radiotherapy within 90 days of the operation, and chemotherapy within 30 days of the operation. Medical comorbidities include diabetes, dyspnea, chronic obstructive pulmonary disease (COPD), hypertension, history of myocardial infarction, a previous percutaneous coronary intervention (PCI) or cardiac surgery, and a previous stroke or transient ischemic attack (TIA).
2.3
Statistical analysis
Unadjusted risk factors for readmission as well as 30-day complication profiles for both cohorts were calculated using Pearson’s chi-square or Fisher’s exact tests for categorical variables and Student t-tests for quantitative variables. A multiple logistic regression model was used to control for potential confounding variables and to identify independent risk factors for unplanned 30-day readmission and 30-day reoperation within the study population. Categorical variables with at least five events in the readmitted and not-readmitted cohort, as well as all continuous variables and 30-day complications were included in the regression models. Additionally, the sum of the relative value units (RVUs) for additional procedures was included to adjust for the added complexity and risk of concurrent procedures, as has been described previously . Hosmer–Lemmeshow (HL) and C -statistics were computed to assess model calibration and discrimination .
2
Methods
2.1
Data acquisition and patient selection
The American College of Surgeons NSQIP registry is a validated, national surgical outcomes database, aimed at measuring and improving upon the quality of care delivered to surgical patients across the United States. Data collection methods for the NSQIP registry have been previously described in detail . In brief, these data are independently abstracted by trained surgical nurses and are subject to random audits providing a high quality, standardized database that has a demonstrated disagreement rate of less than 1.8%. The NSQIP database was retrospectively queried for data on all patients undergoing an outpatient thyroidectomy in 2011 at over 350 participating institutions.
Patients undergoing thyroidectomy were identified using the Current Procedural Terminology codes 60220, 60225, 60240, 60252, 60254, 60270, and 60271 ( Table 1 ). Outpatient procedures were identified by the inpatient/outpatient variable in the NSQIP registry. Of note, outpatient surgery is defined as one requiring less than 23 hours stay in hospital.
| 60220 | Total thyroid lobectomy, unilateral; with or without isthmusectomy |
| 60225 | Total thyroid lobectomy, unilateral; with contralateral subtotal lobectomy, including isthmusectomy |
| 60240 | Thyroidectomy, total or complete |
| 60252 | Thyroidectomy, total or subtotal for malignancy; with limited neck dissection |
| 60254 | Thyroidectomy, total or subtotal for malignancy; with radical neck dissection |
| 60270 | Thyroidectomy, including substernal thyroid; sternal split or transthoracic approach |
| 60271 | Thyroidectomy, including substernal thyroid; cervical approach |
2.2
Outcomes and risk adjustment variables
The primary outcomes of interest were unplanned 30-day hospital readmission and 30-day reoperation. Readmissions included hospitalization to either the same or another hospital after the initial surgical procedure. Hospitalizations within 30 days of discharge that were planned at the time of surgery were not included. The ACS-NSQIP participant use file’s readmission data has been previously validated and shown to accurately capture unplanned readmission events . Reoperation was defined as an unplanned return to the operating room for a surgical procedure related to either the index or a concurrent procedure.
Secondary outcomes of interest were overall morbidity, surgical complications, overall medical complication, and death within 30 days of the operation. Overall 30-day morbidity was defined as the presence of one or more perioperative surgical or medical complications. Surgical complications included superficial, deep, and organ/space surgical site infections (SSI) and wound dehiscence. Medical complications included deep vein thrombosis, pulmonary embolism, ventilator dependence for > 48 hours, unplanned re-intubation, pneumonia, renal insufficiency, acute renal failure, urinary tract infection, coma, stroke, peripheral nerve injury, cardiac arrest, myocardial infarction, bleeding requiring transfusion, and sepsis or septic shock. Reoperation was defined as an unplanned return to the operating room for a surgical procedure related to either the index or a concurrent procedure.
Preoperative variables collected by NSQIP include demographic data, medical comorbidities, operative time, and concurrent surgical procedures. Patient demographics collected include age, body-mass index (BMI), race, gender, active smoking status, steroid use, radiotherapy within 90 days of the operation, and chemotherapy within 30 days of the operation. Medical comorbidities include diabetes, dyspnea, chronic obstructive pulmonary disease (COPD), hypertension, history of myocardial infarction, a previous percutaneous coronary intervention (PCI) or cardiac surgery, and a previous stroke or transient ischemic attack (TIA).
2.3
Statistical analysis
Unadjusted risk factors for readmission as well as 30-day complication profiles for both cohorts were calculated using Pearson’s chi-square or Fisher’s exact tests for categorical variables and Student t-tests for quantitative variables. A multiple logistic regression model was used to control for potential confounding variables and to identify independent risk factors for unplanned 30-day readmission and 30-day reoperation within the study population. Categorical variables with at least five events in the readmitted and not-readmitted cohort, as well as all continuous variables and 30-day complications were included in the regression models. Additionally, the sum of the relative value units (RVUs) for additional procedures was included to adjust for the added complexity and risk of concurrent procedures, as has been described previously . Hosmer–Lemmeshow (HL) and C -statistics were computed to assess model calibration and discrimination .
3
Results
3.1
Thirty-day outcomes
In total 5121 patients were identified to have undergone an outpatient thyroidectomy in 2011. Overall 30-day morbidity was rare with only 47 patients (0.92%) experiencing any perioperative morbidity. SSI was most common single complication with 19 total incidences (0.37%). With the exception of 1 deep incisional SSI, all others were superficial SSIs; no organ/space SSIs were reported. Five additional patients experienced wound disruptions, yielding a total of 24 (0.47%) patients with a surgical complication. Individual medical complications were also rare ( Table 2 ). The most common medical complication was urinary tract infection with 11 total instances (0.21%). Five patients (0.10%) underwent unplanned re-intubation and 3 (0.06%) contracted pneumonia. Overall, 23 patients (0.45%) experienced a 30-day postoperative medical complication. Of the 5121 patients, 111 (2.17%) were readmitted within 30 days and 48 (0.94%) underwent reoperation. Mortality was rare, with only 1 reported case in the not-readmitted cohort ( Table 3 ). A complete 30-day complication profile for both cohorts is available in Table 3 .
| Outpatient thyroidectomy ( n = 5121) | ||
|---|---|---|
| n | % | |
| Any 30-day complication | 47 | 0.92% |
| Overall surgical complication | 24 | 0.47% |
| SSI | 19 | 0.37% |
| Superficial SSI | 18 | 0.35% |
| Deep incisional SSI | 1 | 0.02% |
| Organ/Space SSI | 0 | 0.00% |
| Wound disruption | 5 | 0.10% |
| Overall medical complication | 23 | 0.45% |
| Pneumonia | 3 | 0.06% |
| Unplanned intubation | 5 | 0.10% |
| VTE | 1 | 0.02% |
| Deep vein thrombosis | 1 | 0.02% |
| Pulmonary Embolism | 1 | 0.02% |
| Failure to wean | 0 | 0.00% |
| Progressive renal insufficiency | 0 | 0.00% |
| Acute Renal Failure | 0 | 0.00% |
| Urinary tract infection | 11 | 0.21% |
| Stroke | 1 | 0.02% |
| Coma | 0 | 0.00% |
| Peripheral nerve injury | 1 | 0.02% |
| Cardiac arrest | 1 | 0.02% |
| Myocardial infarction | 0 | 0.00% |
| Bleeding | 1 | 0.02% |
| sepsis or septic shock | 1 | 0.02% |
| Sepsis | 1 | 0.02% |
| Septic shock | 0 | 0.00% |
| Hospital readmission | 111 | 2.17% |
| Reoperation | 48 | 0.94% |
| Death | 1 | 0.02% |
| Not-readmitted | Readmitted | p -Value | |||
|---|---|---|---|---|---|
| n = 5010 (97.83%) | n = 111 (2.17%) | ||||
| Age, years | 51.03 ± 14.36 | 51.41 ± 15.50 | 0.783 | ||
| BMI, kg/m 2 | 29.55 ± 7.45 | 30.25 ± 6.32 | 0.325 | ||
| Gender, % female | 4084 | 81.52% | 85 | 76.58% | 0.183 |
| Race | 0.933 | ||||
| White | 3793 | 75.71% | 87 | 78.38% | |
| Black | 568 | 11.34% | 11 | 9.91% | |
| Asian | 208 | 4.15% | 4 | 3.60% | |
| Other | 441 | 8.80% | 9 | 8.11% | |
| Diabetes | 540 | 10.78% | 12 | 10.81% | 0.991 |
| Current smoker | 754 | 15.05% | 18 | 16.22% | 0.734 |
| Dyspnea | 387 | 7.72% | 12 | 10.81% | 0.230 |
| History of COPD | 92 | 1.84% | 7 | 6.31% | 0.001 |
| Congestive heart failure | 3 | 0.06% | 0 | 0.00% | 1.000 |
| History of myocardial infarction | 6 | 0.22% | 0 | 0.00% | 0.723 |
| Hypertension | 1864 | 37.21% | 50 | 45.05% | 0.091 |
| Steroid | 82 | 1.64% | 3 | 2.70% | 0.433 |
| Bleeding disorders | 46 | 0.92% | 3 | 2.70% | 0.089 |
| Chemotherapy | 5 | 0.18% | 1 | 1.75% | 0.117 |
| Radiotherapy | 3 | 0.11% | 0 | 0.00% | 1.000 |
| Prior operation within 30 days | 12 | 0.43% | 0 | 0.00% | 1.000 |
| History of PCI and cardiac surgery | 79 | 2.90% | 4 | 7.02% | 0.088 |
| History of stroke and TIA | 83 | 3.05% | 2 | 3.51% | 0.693 |
| Operative time, min | 107.21 ± 52.14 | 114.36 ± 67.13 | 0.158 | ||
| Surgical complication | 21 | 0.42% | 3 | 2.70% | < 0.001 |
| Medical complication | 17 | 0.34% | 6 | 5.41% | < 0.001 |
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