Abstract

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.

Keywords: Complications, Lymphocyte, Neutrophil, Prognosis, Spinal fusion

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.

Declaration of patient consent

Patient’s consent not required as patients identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1. Diem S, Schmid S, Krapf M, Flatz L, Born D, Jochum W. Neutrophil-to-lymphocyte ratio (NLR) and platelet-tolymphocyte ratio (PLR) as prognostic markers in patients with non-small cell lung cancer (NSCLC) treated with nivolumab. Lung Cancer. 2017. 111: 176-81

2. Inose H, Kobayashi Y, Yuasa M, Hirai T, Yoshii T, Okawa A. Postoperative lymphocyte percentage and neutrophillymphocyte ratio are useful markers for the early prediction of surgical site infection in spinal decompression surgery. J Orthop Surg. 2020. 28: 2309499020918402

3. Iwata E, Shigematsu H, Okuda A, Morimoto Y, Masuda K, Nakajima H. Lymphopenia at 4 days postoperatively is the most significant laboratory marker for early detection of surgical site infection following posterior lumbar instrumentation surgery. Asian Spine J. 2016. 10: 1042-6

4. Kakhki RD, Dehghanei M, ArefNezhad R, Motedayyen H. The predicting role of neutrophil lymphocyte ratio in patients with acute ischemic and hemorrhagic stroke. J Stroke Cerebrovasc Dis. 2020. 29: 105233

5. Manuel V, Miana LA, Guerreiro GP, Tenório DF, Turquetto A, Penha JG. Prognostic value of the preoperative neutrophil-lymphocyte ratio in patients undergoing the bidirectional Glenn procedure. J Card Surg. 2020. 35: 328-34

6. Manuel V, Miana LA, Turquetto A, Guerreiro GP, Fernandes N, Jatene MB. The role of the neutrophil-lymphocyte ratio for pre-operative risk stratification of acute kidney injury after tetralogy of Fallot repair. Cardiol Young. 2021. 31: 1009-14

7. Shen CJ, Miao T, Wang ZF, Li ZF, Huang LQ, Chen TT. Predictive value of post-operative neutrophil/lymphocyte count ratio for surgical site infection in patients following posterior lumbar spinal surgery. Int Immunopharmacol. 2019. 74: 105705

8. Wu X, Luo Q, Su Z, Li Y, Wang H, Yuan S. Prognostic value of preoperative absolute lymphocyte count in children with tetralogy of fallot. J Am Heart Assoc. 2021. 10: e019098