Study design: Case-control study.
Objective: To compare intraoperative bleeding, drainage, and hidden blood loss (HBL) of posterior lumbar interbody fusion (PLIF) on lumbar spinal stenosis (LSS) in patients with rheumatoid arthritis (RA) and non-RA and identify the risk factors of HBL with RA.
Summary of background data: Exploration on PLIF on LSS and HBL has been reported before while the comparison on total blood loss (TBL), especially HBL of PLIF or PLF on LSS between patients with RA and without RA has not been studied.
Methods: Sixty-one patients diagnosed LSS with RA (RA group) and 87 matched patients without RA (NRA group) were enrolled and demographic characteristics, RA-related parameters, operation and blood loss information were extracted. Intraoperative blood loss, drainage, and HBL were primary outcomes and secondary measures included operation time, hematocrit (Hct) and hemoglobin (Hb), the number of anemia and blood transfusion.
Results: There was no statistical difference in total blood loss (TBL), intraoperative blood loss, and postoperative drainage while HBL and the proportion of HBL in TBL were lower in NRA group (P < 0.001 and P = 0.012, respectively). Stratified analysis based on the number of surgical levels suggested HBL and the proportion of HBL in NRA group was superior in long-segment surgery (>2 segments). The secondary outcomes showed the change of Hct was lower in NRA group (P = 0.021) but not the reduction of Hb. In addition, there was no significant difference in neoformative and grade-aggravated anemia, as well as the number of allogeneic blood transfusion and operation time showed Steinbroker classification, disease-modifying anti-rheumatic drugs (DMARDs), hange of Hb and allogeneic blood transfusion were risk factors for HBL with RA.
Conclusion: There was no difference in TBL, intraoperative bleeding, and operation time, but HBL were higher in RA patients particularly in long-segmental operation. Steinbroker classification, DMARDs, the change of Hb, and allogeneic blood transfusion were independent risk factors for HBL in RA patients.
Level of evidence: 3.