A study presented at the North American Spine Society Annual Meeting in Los Angeles found that among patients undergoing one- or two-level anterior cervical diskectomy and fusion (ACDF), 3 percent were readmitted within 30 days of surgery, and half of those readmissions were unrelated to neck surgery.

David C. Sing, MD, who presented the study in a Best Papers session, said the results indicate a need “to improve our understanding of which patients may be at higher risk for readmission, in hopes of reducing readmissions and improving continuity of care at discharge.”

Study sample and outcome measures

The study involved 18,833 patients undergoing ACDF between 2012 and 2016. Of those, 15,464 (82.1 percent) had single-level ACDF and 3,369 (17.9 percent) had two-level ACDF. Mean patient age was 53.7 years, and 50 percent in both the one- and two-level fusion groups were male. Overall, 36.8 percent of the patients were younger than 50 years, 53.6 percent were between 50 and 69 years, and 9.6 percent were 70 years or older. Among all patients undergoing ACDF, 46.8 percent were obese, and 44.2 percent had a history of diabetes.

Patients undergoing surgery for oncologic, traumatic, infectious, or revision indications and those undergoing combined anterior-posterior cervical fusion were excluded. Patients with positive steroid use but who received short-course steroids (duration of 10 days or fewer) in the 30 days prior to surgery were not included.

The primary outcome measures were complications or unplanned readmissions within 30 days of surgery. Major complications included death, sepsis, deep surgical site infection (SSI), pulmonary embolism, ventilator usage for longer than 48 hours, unplanned intubation, cardiac arrest requiring cardiopulmonary resuscitation, and return to the operating room. Minor complications were superficial SSI, pneumonia, urinary tract infection, deep vein thrombosis or thrombophlebitis, and transfusion.

Causes for unplanned readmissions were investigated and categorized as those related and unrelated to the surgical site. Those related to the surgical site included dysphagia, acute postoperative pain, edema/hematoma/seroma, radiculopathy/myelopathy, and deep SSI/hardware infections. Those unrelated to the surgical site included pneumonia, gastrointestinal disorders, sepsis/septic shock/other
infectious disorders, and cardiac disorders. Data on timing of readmission for each category also were collected and analyzed.

Study outcomes

The overall rate of any postoperative complication was 3.6 percent for all ACDFs, 4.3 percent in two-level fusions, and 3.5 percent in single-level fusion (P = 0.027). Major complications were present in 2.9 percent of two-level fusions and 2.3 percent of single-level fusions (P = 0.015). In total, 569 unplanned readmissions (3 percent) were identified, of which 39.5 percent were related to the surgical site and 49.7 percent were unrelated to the surgical site. The other 10.5 percent were due to unknown causes, as some readmission data were not available. The most frequent reason for 30-day readmission was pneumonia, accounting for 9.3 percent of readmissions, with a mean time to readmission of 11.3 days, followed by dysphagia (7.4 percent; mean time to readmission, 6.3 days), acute postoperative pain (7.2 percent, 11.4 days), and edema/hematoma/seroma (7.0 percent, 7.4 days). Other common causes of readmission related to surgical site included radiculopathy/myelopathy and deep SSI/hardware infections. Causes of readmission unrelated to the surgical site included gastrointestinal disorder and sepsis.

The most influential independent risk factors for readmission identified via multivariate analysis were American Society of Anesthesiology (ASA) score ≥ 3 (odds ratio [OR], 1.96; 95 percent confidence interval [CI], 1.6–2.4; P < 0.001), history of steroid use (OR, 1.76; 95% CI, 1.3–2.5; P < 0.001), and age ≥ 70 years (versus younger than 50 years, OR, 1.66; 95% CI, 1.2–2.2; P < 0.001). The most influential risk factors for any adverse event were dependent functional status (OR, 3.0; 95% CI, 2.2–4.2; P < 0.001), age ≥ 70 years (versus younger than 50 years, OR, 2.76; 95% CI, 2.1–3.6; P < 0.001), and ASA score ≥ 3 (OR, 1.8; 95% CI, 1.5–2.1; P < 0.001).

The authors said a key finding of this study is that, of the 49.7 percent of readmissions unrelated to the surgical site, the most common reason was pneumonia (9.3 percent). Pneumonia, they noted, plays a common role in the development of sepsis and mortality, with reports of 10 percent of sepsis and 20 percent of mortality cases attributable to pneumonia as the inciting complication in patients having undergone posterior lumbar fusions. Patients with chronic obstructive pulmonary disease and chronic steroid use are at a greater risk of developing postoperative pneumonia.

Regarding the 39.5 percent of readmissions that were related to the surgical site—including dysphagia, acute postoperative pain, and edema/hematoma/seroma—the authors said the dysphagia rate of 7.4 percent is in line with the 4.8 percent to 8 percent range reported in various other studies. Prospective studies indicate that the incidence and severity of postoperative dysphagia decrease over time.

Implications

The authors characterized as “staggering” the 7 percent rate of readmissions specifically related to edema/hematoma/seroma development at the surgical site. This finding, they said, “strongly suggests that monitoring of wound status could significantly reduce the rate of unplanned readmissions in high-risk patients having undergone cervical fusions.” Their other recommendations were post-discharge follow-up with primary care providers emphasizing pneumonia screening and attentive management of post-discharge pain.

Dr. Sing commented, “No surgeon is happy to get a call during dinner time about a patient who is back in the hospital unexpectedly. Fortunately, this is uncommon with ACDF cases, which makes it difficult to study. This is a large-scale study that gives surgeons more insight into the most common reasons for readmissions (pneumonia, dysphagia, and postoperative pain), and it establishes groundwork for future studies to evaluate interventions that may reduce these readmissions.”

The natural follow-up to this study, he said, would be “to work on reducing common readmissions, such as pneumonia. Though many hospitals already institute incentive spirometry and other precautions to reduce the risk of pneumonia, there may be benefit in continuing these precautions once discharged. Alternatively, improving awareness at rehabilitation facilities of common complications may help identify ways to reduce risk in the postoperative course.”

*Criteria for complications are defined in the National Surgical Quality Improvement Program Participant Use File, available at www.facs.org/quality-programs/acs-nsqip/participant-use.

Dr. Sing’s coauthors of “Half of Unplanned Readmissions Following One- or Two-Level Anterior Cervical Decompression and Fusion Are Unrelated to Surgical Site” are Molly Yora, BS, and Chadi Tannoury, MD.

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org.