Preoperative lymphocyte percentage and neutrophil-lymphocyte ratio are useful predictors of 30-day postoperative complications after lumbar fusion.

Background: Lymphocyte percentage/count, platelet-lymphocyte ratio (PLR), and neutrophil-lymphocyte ratio (NLR) have shown prognostic significance in patients with cancer, stroke, and following cardiac surgery. However, the utility of these blood parameters for assessing the 30-day postoperative risk for lumbar fusion complications has not been established.
Methods: In this single-center-single-surgeon retrospective series, 77 consecutive patients underwent one- or two-level lumbar fusion. Lymphocyte percentage/count, PLR, and NLR were investigated as predictors of 30-day postoperative complications.
Results: Ten of 77 patients had postoperative complications. A unit increase in NLR and lymphocyte percentage was significantly associated with a 23% increase and 7% decrease, respectively, in the odds of a complication occurring. Preoperative NLR ≥ 2.32 and lymphocyte percentage ≤ 29.5% significantly discriminated between the "complication" and "no-complication" groups.
Conclusion: Patients with a preoperative lymphocyte percentage of ≤29.5% and/or NLR ≥2.32 should be closely monitored as high-risk groups susceptible to 30-day postoperative complications after lumbar fusion. Copyright:

INTRODUCTION

The importance of preadmission/preoperative lymphocyte percentage/count, platelet-lymphocyte ratio (PLR), and neutrophil-lymphocyte ratio (NLR) as prognostic markers following cardiac surgery, stroke, and cancers has been extensively reported.[1,4-6,8] Some spine surgery studies have also reported that lymphocyte count/percentage and NLR levels obtained between 3 and 7 days postoperatively helped predict whether surgical site infections (SSIs) would occur within 30 postoperative days.[2,3,7] Here, we investigated whether preoperative lymphocyte percentage/count, PLR, and NLR are useful predictors for 30-day postoperative complications following lumbar fusion.

MATERIALS AND METHODS

Study design

In this case–control study, 77 adults underwent elective single- (37 patients) or two-level (40 patients) posterior/posterolateral lumbar fusion performed by one surgeon (2012–2019) [Tables 1 and 2].

Table 1:

Inclusion and exclusion criteria.

Table 2:

Summary of variables investigated.

Statistical analysis

Statistical analysis was performed on IBM SPSS Statistics 27 (Windows). Binary logistic regression, receiver operating characteristics, and Youden’s index were utilized [Table 3].

Table 3:

Statistical tests utilized at a 5% significance level with the occurrence of 30-day complications as the outcome measure.

RESULTS

Correlation between 30-day postoperative complications and lymphocyte percentage and NLR

[Table 4] is a summary of the patients’ baseline characteristics. Postoperative complications occurred in 10 out of 77 patients (13%); three developed SSI, three pneumonia, and one with each of the following: atelectasis, gastroenteritis, peritonitis, and transient ischemic attack [Figure 1]. A unit increase in NLR and lymphocyte percentage was significantly associated with a 23% increase and 7% decrease, respectively, in the odds of a complication occurring. There were no statistically significant associations between the occurrence of complications and the other independent variables [Figure 2 and Table 5].

Table 4:

Patient demographic and operative data.

Figure 1:

Incidence and types of postoperative complications (n = 77). SSI: Surgical site infection, TIA: Transient ischemic attack.

Figure 2:

Odds ratio with 95% confidence interval for the occurrence of complications within 30 days after lumbar fusion according to demographic/surgical/laboratory parameters. a compared to female, b compared to nonsmokers, c compared to two-level fusion. *Statistically significant.

Table 5:

Odds ratio for the occurrence of complications within 30 days after lumbar fusion surgery.

Predictive value of preoperative lymphocyte percentage and NLR for determining 30-day postoperative complications

The area under the curve values for the preoperative NLR and lymphocyte percentage were in the “acceptable” range (0.7–0.8) of prognostic accuracy for postoperative 30-day complications. The optimal cutoff value for preoperative NLR and lymphocyte percentage were ≥2.32 and ≤29.5%, respectively [Figure 3]. Compared to others, patients with a preoperative NLR ≥2.32 and those with a lymphocyte percentage ≤29.5% had 5.6 times and 13.9 times greater odds of postoperative complications, respectively [Figure 4].

Figure 3:

ROC analysis for preoperative (a) neutrophillymphocyte ratio and (b) lymphocyte percentage in discriminating between complication and no complication patients after lumbar fusion.

Figure 4:

Odds ratio with 95% confidence interval for the occurrence of complications according to NLR and lymphocyte percentage cutoff values. a compared to NLR less than 2.32, b compared to lymphocyte percentage greater than 29.5%. *Statistically significant.

DISCUSSION

We investigated the preoperative predictors of postoperative complications after lumbar fusion. Patients with preoperative lymphocyte percentage ≤29.5% and/or NLR ≥ 2.32 had a higher risk of developing postoperative complications. Other studies have reported similar findings (i.e., high baseline/ preoperative NLR and lymphocytopenia were predictors of worse outcomes).[1,4-6,8] Nevertheless, spine surgery biomarker studies found no statistically significant association between preoperative NLR or lymphocyte count/percentage and the development of postoperative SSI [Table 6].[2,7] These contradictory results, as we observed in our study, could be because preoperative NLR and lymphocyte percentage predicted the development of any complication but not specifically SSI. High NLR and/or decreased lymphocyte percentage may reflect an activated immune system and a heightened systemic inflammatory response to operative stress. This increases intraoperative cytokines that release damaging oxygen-derived free radicals, contributing to worse outcomes.[5,8]

Table 6:

Summary of selected literature on the prognostic value of preoperative NLR and/or lymphocyte percentage.

CONCLUSION

A raised NLR (≥2.32) and/or decreased lymphocyte percentage (≤29.5%) at baseline predict the development of postoperative complications after lumbar fusion.