Table 2. Characteristics of the included studies on the use of drains and dressings in spine surgery.

SSI: surgical site infection; PPV: positive predictive value; NPV: negative predictive value; TXA: tranexamic acid; MIC: minimum inhibitory concentration 

Author(s)	Country	Year	Study design	Sample size	Patient demographics	Type of surgery	Key findings
Choi et al. [3]	South Korea	2016	Retrospective study	70	34 men, 36 women, mean age 48.19 years	Single-level lumbar discectomy	Surgical drains did not elevate postoperative infection; Drain tip cultures allowed early detection of infection leading to faster antibiotic treatment
Kobayashi et al. [4]	Japan	2017	Retrospective cohort study	329	Adults, 54.4% female	Various spinal surgeries (cervical, thoracic, lumbar, sacral)	Drain tip cultures useful for early detection of SSI, especially methicillin-resistant bacteria; overall low PPV and high NPV for predicting wound infection
Poorman et al. [7]	USA	2014	Retrospective case-control	81	Adult patients	One- and two-level cervical spine fusions	No significant difference in complications, but longer operative time and hospital stay in drain group
Herrick et al. [8]	USA	2018	Multicenter retrospective study	1799	Adult patients	Posterior cervical decompression with instrumentation	Drains not associated with lower reoperation for hematoma, but may reduce SSI reoperations
Elfiky et al. [9]	Egypt	2022	Prospective randomized study	62	Age range 23-69, 51.6% female	Single-level posterior lumbar interbody fusion (PLIF)	Natural drainage reduced total blood loss compared to negative drainage without significant differences in postoperative outcomes
Cabrera et al. [10]	Various	2023	Cross-sectional survey	231	Surgeons 95.2% male, ages 25-65+	Open lumbar fusion surgery for degenerative pathologies	Most spine surgeons worldwide prefer to place a subfascial wound drain for degenerative open lumbar surgery, with removal based on time (mostly two days) or output criteria
Liu et al. [11]	China	2016	Meta-analysis	1904	Not specified	Posterior spinal surgery (various procedures)	No obvious evidence to support the application of closed suction drains for posterior spinal surgery. Drainage did not reduce infection, hematoma, or postoperative neurological injury.
Walid et al. [12]	USA	2012	Retrospective study	402	Mean age 57.3 years, 57% female, BMI 31.3 kg/m², 29.1% diabetic	Lumbar decompression and fusion (LDF)	Drain use did not significantly increase the risk of wound infection; Increased prevalence of postoperative fever and need for blood transfusion in drained group; No significant economic impact on hospital length of stay or charges except in lateral procedures
Kim et al. [13]	South Korea	2023	Retrospective study	1415	Mean age 64.9 years, 49% male	Cervical, lumbosacral, and thoracic spine surgeries	Drain tip cultures not useful for predicting SSI due to low positive predictive value; High positivity rate in SSI group
Chen et al. [14]	China	2018	Retrospective study	1125	17 women, 9 men, mean age 62.12 ± 10.42 years, mean BMI 28.88 ± 2.90 kg/m²	Lumbar spine surgery (discectomy, decompression, instrumented fusion)	No significant differences between single-tube and double-tube drainage methods in most aspects; Single-tube drainage group had better clinical outcomes and shorter hospital stays
Shi et al. [15]	China	2021	Case-control study	743	Comparable demographic characteristics (age, gender, BMI, medical history)	Posterior one-level or two-level lumbar fusion with instrumentation	Time-driven wound drain removal is associated with less postoperative drain output, less total blood loss, earlier ambulation, and shorter hospital stay compared to output-driven removal, without increasing the incidence of SSI or symptomatic spinal epidural hematoma (SHE).
Eckardstein et al. [16]	Germany	2015	Survey study	163	Not applicable (survey of surgeons)	Various spinal surgeries	Factors influencing drain use include type of surgery, size of wound, hemostasis at the end of procedure, and use of anticoagulatory drugs. Use of drains in spine surgery is with no clear guidelines. Most drains are discontinued by day 4, with time-driven removal more common in less invasive surgeries and output-driven removal in more invasive procedures.
Pennington et al. [17]	UK	2019	Retrospective cohort study	38	Adult patients, greater BMI, more likely to have diabetes and hypertension	Posterior spinal fusion	No clear benefit of closed suction drains in reducing infection or hematoma rates; higher transfusion rates in drain group
Gubin et al. [18]	Russia	2018	Randomized open-label trial	155	Adults (18-80 years)	Multi-level posterior spinal surgery	No-drain group had lower perioperative blood loss and transfusion requirements but higher postoperative aspirations
Adogwa et al. [19]	USA	2018	Retrospective cohort study	139	Adult spinal deformity patients	Spinal decompression and fusion	Use of postoperative subfascial drains may not reduce SSI or hematoma formation rates; associated with higher intraoperative blood loss and longer hospital stays
Pivazyan et al. [20]	Armenia	2023	Systematic review and meta-analysis	2446	Adult patients	Posterior spinal surgery	Prolonged prophylactic systemic antibiotics do not significantly reduce SSI rates in patients with closed suction drains after posterior spinal surgery
Liang et al. [21]	China	2019	Retrospective clinical trial	60	Adult patients with degenerative lumbar scoliosis	Posterior lumbar decompression and fusion of 3+ levels	Topical injection of TXA via drain and drain-clamping reduces postoperative blood loss and hospital stay in degenerative lumbar scoliosis surgery without increasing complications
Armaghani et al. [22]	USA	2014	Retrospective cohort analysis	25	Pediatric patients (mean age 13.5 years)	Posterior spinal fusion for spinal deformity	Topical application of vancomycin powder in pediatric spinal deformity surgery provides local antibiotic concentration above MIC for at least two days postoperatively without reaching toxic serum levels
Brown et al. [23]	USA	2004	Prospective randomized study	83	Adult patients	Extensive lumbar spine surgery	The decision to use or not use a wound drain following extensive lumbar spine surgery should be left to the surgeon's discretion as it does not significantly alter infection, hematoma, or neurological deficit rates