JPM | Free Full-Text | Similar Short-Term Outcomes of Adolescent Idiopathic Scoliosis Surgery with or without Drainage: A Systematic Review of the Literature and Meta-Analysis
2. Materials and Methods
A systematic review of the literature regarding the use of closed suction drainage in adolescent idiopathic scoliosis surgery was conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines [5].
Only peer-reviewed publications were considered for inclusion. Studies which compared the outcomes of patients who underwent surgical correction of AIS through the posterior-only approach with and without the use of closed suction drainage were included. Only articles in English that met the PICO (Population, Intervention, Comparison, and Outcomes) criteria on systematic reviews were included.
Only randomized controlled trials (RCTs), prospective and retrospective cohort studies (PCS and RCS) were considered for inclusion. In vitro studies and animal model studies were excluded, as well as case reports and case series.
This systematic review has not been registered.
2.1. Search Strategy
Studies eligible for this systematic review were identified through an electronic systematic search of PubMed and the Cochrane Central Registry of Controlled Trials until August 2023.
The following search strings were used:
2.2. Study Selection
Articles considered relevant by electronic search were retrieved in full-text, and hand searches of their bibliographies were performed to find further related articles. Reviews and meta-analyses were also analyzed to identify potentially missed eligible papers. Duplicates were removed. The study selection process was carried out in accordance with the PRISMA flowchart (Figure 1). After full text screening, records that did not meet the eligibility criteria were excluded. Remnant studies were categorized by type, according to the Oxford Centre for Evidence-Based Medicine (OCEBM).
2.3. Data Collection Process
All included studies were analyzed, and data related to post-operative outcomes of interest were extracted and summarized by two distinct authors (M.T. and M.M.).
Meta-analyses were performed when there were at least three studies to be compared. Heterogeneity between studies was assessed using the inconsistency statistic (I2 > 75% was considered as high heterogeneity). Publication biases were assessed with Egger’s test and represented with forest plots. Log odds ratios or standardized mean differences were used as measures of effect size. A random effect model was applied. A p-value of < 0.05 was considered to be significant. All statistical analyses were conducted with Jamovi version 2.2 (The Jamovi Project, Sydney, Australia) software.
4. Discussion
The main finding of the present study is that the current available literature does not exhibit significant differences in short-term outcomes of AIS surgery whether the drain was applied or not, in terms of SSI, re-intervention rate, need for blood transfusion, and hospital length of stay.
Closed suction drainage in the setting of AIS surgery is intended to remove the blood and serum from the surgical site to avoid post-operative hematoma and subsequent consequences like wound complications, compression of exposed neural elements, and deep SSI [3,12]. To date, drains are mainly used based on the surgeon’s experience and intra-operative findings like quality of hemostasis achieved, invasiveness of the surgical procedure, and eventual exposure of the dura and neural elements. The advantages of drainage following AIS surgery are still debatable [4,13]. A consensus on whether using a drain or not in the setting of AIS surgery has not yet been reached.
Alongside the evolution of surgical techniques, post-operative protocols of AIS have also undergone major improvements. ERAS (enhanced recovery after surgery) protocols are nowadays applied in several institutions as multimodal and multidisciplinary approaches for improving perioperative outcomes of patients, reducing the hospital length of stay with an adjunctive positive financial impact on healthcare management. They imply multimodal analgesia, early patient mobilization, a bowel care regime, an early urinary catheter, and post-operative drain removal [14]. Intra-operative strategies of ERAS protocols often include avoidance of drains if possible [15]. Few authors reported no increase in blood loss, transfusion requirements, wound infection, skin dehiscence, and wound hematoma after AIS surgery without using drain [16]. Potential disadvantages of drains include impeded mobilization, increased discomfort, and increased need for post-operative care, such as stripping or reservoir emptying [3].
Previous literature has evaluated potential risks of drain use in lumbar spinal surgery and hip and knee arthroplasties, revealing a tendency for patients in which the drain was applied to receive more postoperative blood transfusions and to have a longer postoperative hospital stay [17,18,19,20,21].
Helenius et al., Diab et al., and Blank et al. reported higher overall transfusion rates in patients in the no-drain group [3,9,10], whereas Kochai et al. and Ovadia et al. reported a higher overall transfusion rate in patients from the drain group [8,11]. Overall meta-analysis showed a surprisingly slight tendency of patients in the no-drain group to require more blood transfusions overall. Some authors hypothesize that drainage prevents tamponade, resulting in greater post-operative blood loss and a subsequent higher blood transfusion rate [9]. Although closed suction drainage may obstruct tamponade following hip or knee arthroplasty, this phenomenon might be of weaker importance in patients undergoing AIS surgery, primarily because of prolonged post-operative supine positioning that simultaneously results in compression of the surgical site, reducing dead space, and thus mechanically tamponing the bleeding. This fact becomes more relevant when the spinous processes and posterior elements are left intact, allowing for an effective bony attachment of paravertebral muscle. Helenius et al. [10] reported that around 15% of patients required posterior column osteotomies (PCOs) that are known to increase post-operative blood loss and requirement for blood transfusion [22], and Diab et al. [3] reported that around 10% of patients underwent thoracoplasties. In addition, overall transfusion rates may be influenced by many variables, firstly, the intra-operative transfusion rate. Evaluation of the post-operative transfusion rate alone was not possible due to lack of data in the included studies. The overall transfusion rate was regarded as an estimate of the post-operative transfusion rate, as there was no statistically significant difference between the drain and no-drain group in terms of intraoperative transfusion rates in any of the included studies. No difference in overall transfusion rates was found at meta-analysis between patients in the drain and no-drain groups. However, the limitations in the included studies make this data difficult to explain, as the comparability of patient groups is hindered by the lack of data regarding the invasiveness of the applied procedures, despite the comparability in the severity of the deformity and the average number of fused levels for all the studies, as shown in Table 2.
As for hospital length of stay, overall meta-analysis showed a moderately longer length of stay in patients of the drain group, with a standardized mean difference of +0.22 days. Ovadia et al. [8] reported longer LOS in patients of no-drain group. However, statistical significance was not reached; this finding is still important since in the current literature, the average difference in LOS between traditional postoperative protocols and ERAS protocols was 1.4–1.6 days. No ERAS protocol was reported to be applied in the included studies. Viewed in this perspective, the data may indicate that the absence of drainage might account for up to a 15% reduction in LOS and the significance of the data might not become evident in a setting that does not implement fast track protocols.
As for complications, Helenius et al., Ovadia et al., and Diab et al. reported a higher SSI rate among patients in the no-drain group, whereas Kochai et al. reported a higher SSI rate in patients from the drain group [3,8,10,11]. Overall meta-analysis showed a slight tendency for patients in whom a drain was not applied to be more likely to develop SSI, although statistical significance was not reached. The higher surgical site infection rate in one group compared to the other can be explained by two opposite pathophysiological mechanisms. The first involves the drain, which acts as a potential pathway for external contamination to reach the surgical site. The second involves hematoma formation that can facilitate bacterial growth due to a relative hypoxic environment. Looking at the need for re-intervention, Helenius et al., Diab et al., and Blank et al. reported a higher re-intervention rate in the no-drain group [3,9,10], whereas Kochai et al. [11] reported higher need for re-intervention in the drain group. Overall meta-analysis showed a slight inclination of patients in the no-drain group to require re-intervention with a higher probability. Nevertheless, statistical significance was not reached. Notably, the need for surgical revision involves numerous variables and may be attributed to various factors or complications, not limited solely to wound-related issues. Further risks of drainage could be associated with its misplacement, causing pain or compression of neural elements [23].
The studies included in the present work did not show significant differences in overall transfusion rate, SSI rate, length of hospital stay, or overall re-intervention rate at meta-analysis. Consequently, no notable differences were observed in the assessed short-term outcomes of AIS surgery based on whether a drain was used or not. The present study confirms that drain placement should be based on personal experience and intraoperative findings. Furthermore, the drain placement is of mainstay importance in cases involving accessory procedures such as osteotomies and exposure of the dural sac and neural elements.
The present study does not come without limitations. Firstly, the complications resulting from hematoma formation, which is believed to be the main non-infectious complication risk when drainage is not used, could not be evaluated due to the lack of data in the included studies.
The comparability of patients and surgical techniques was limited. Th eincluded studies are heterogeneous regarding study design, randomization of patients, type of spinal instrumentation, accessory procedures applied, drain type (subfascial and subcutaneous), drain placement criteria, drain removal criteria, and surgical technique. Evaluation of post-operative estimated blood loss and post-operative transfusion rate was not possible due to lack of data in the included studies. the included studies are heterogeneous in the formulae used for estimated intra-operative blood loss. In addition, the included studies showed relative inconsistency in the reported outcomes between the drain and no-drain groups that may arise from the variations in study methodologies and patient populations.
The variability in the above-mentioned factors may limit the generalizability of findings.
Finally, the present meta-analysis includes both retrospective comparative studies and randomized clinical trials, which may possibly represent an additional source of bias.
Despite that, to the best of our knowledge, this is the first meta-analysis regarding drainage use in adolescent idiopathic scoliosis surgery.
Further clinical trials that implement the ERAS protocol are required to better evaluate the difference in post-operative outcomes between patients with drains and those without.
