This 14-year comparative cohort study found similar overall and initial procedure recurrence rates for PEF and LFP, with trends suggesting improvements in recurrence with PEF, over the relatively long follow-up for paediatric pilonidal studies. The significantly decreased incidence of wound dehiscence in the PEF cohort compared to the LFP cohort is very promising [3% (n = 1) vs 31% (n = 14); p = 0.0026].
Recurrence is an important issue in the management of PSD and is very common with 19% of all surgeries for PSD in Switzerland and Austria being repeat procedures [13]. Previous studies have shown primary recurrence rates of 15–26% for LFP [6, 14] and 6–17% for fibrin glue techniques [6, 8, 9] in paediatric patients. For comparison, a recurrence rate of 0.2% has been achieved with Bascom and Kardayakis LFP procedures in adults [15], suggesting an increased level of complexity in the management of paediatric patients. The overall recurrence rates observed in this study are slightly decreased compared to those reported for paediatric patients in the literature (3% and 11% for PEF and LFP respectively in this study) over a longer follow-up.
In this study, we utilised a clear definition of recurrence and our 3 distinct metrics to assess outcomes (overall recurrence, initial procedure recurrence and all-cause repeat intervention rates) to be transparent and allow the best assessment of morbidity and treatment success. In contrast, many studies in the literature utilise definitions of overall recurrence/cure rate that allow patients to have repeat procedures for recurrence and yet exclude recurrence as an outcome if the patient is eventually disease free at the end of the follow-up period [6, 8, 9, 16–23]. Though useful, this does not provide the full context of outcomes and can be misleading. Our outcome metrics give more context and detail, allowing clinicians the information to better counsel patients around their likelihood of symptom recurrence and the procedure's success, whilst also enabling better comparison between studies in the literature; as such, we believe this triple-metric methodology should be adopted as the standard.
A median time to symptom recurrence of 0.62 years and 0.27 years (p = 0.0012) for PEF and LFP respectively, alongside the plots shown in Fig. 2, demonstrate that after a single procedure PEF lasts significantly longer than LFP before symptoms recur, in addition to fewer recurrences overall. This study has an overall median follow-up of over 2.5 years, with some patients with over 5 years, which is longer than that of other paediatric PSD studies utilising fibrin glue techniques [9]. Despite this, a limitation of this study and many paediatric pilonidal studies is that patient follow-up does not continue into adulthood hindering interpretation of long-term outcomes. Whilst it is known that the risk of PSD recurrence increases with time [15], all but one of the recurrences observed after primary procedure occurred within 1 year. Symptom recurrence after more than a few years after treatment may be the emergence of new discrete disease in the original region, rather than recurrence of the original disease following treatment.
Wound dehiscence was a common complication in the LFP cohort (31%), whilst all complications were rare in the PEF cohort resulting in a significantly decreased all-cause repeat intervention rate. This demonstrates clear and clinically significant benefits for patients when using the PEF technique. Additional benefits were demonstrated with substantially reduced operative times with PEF than LFP, confirming similar findings in the literature [6, 8]. Previous work has also demonstrated that PEF can easily be performed as a day-case procedure and even solely under local anaesthetic [6]. Moreover, fibrin glue closure has been shown to allow an earlier return to normal activities in 3 days [8], compared to 10–15 days for primary closure techniques [24]. Only 68% of children were found to be back to normal activities at 2 months following Bascom LFP procedures [25]. Minimally invasive treatments of PSD have been shown to improve quality of life more than other methods [26] and subsequently patients significantly prefer them to more extensive traditional procedures [9].
Alternative minimally invasive treatments of PSD to PEF exist with a limited, but growing, evidence base. Examples include injection of phenol solution, endoscopic pilonidal sinus treatment (EPSiT) and laser hair depilation. In comparison to other minimally invasive options, we have demonstrated lower overall recurrence and similar complication rates following PEF (16–23). Direct comparison between studies, however, is difficult given the lack of transparent and precise definitions of recurrence outcomes in the literature. There is substantial scope for future work such as multicentre randomised controlled trials as well as exploration of the use of phenol injection/hair depilation as adjuncts to PEF/endoscopic procedures to identify the ideal minimally invasive treatment regime.
The limitations of this study include a small sample size compared to adult studies, as well as its retrospective methodology. PSD has a wide spectrum of disease severity which can include complex cavities and their associated complications which means a perfect direct comparison of severity between patients is near impossible. Despite being a known risk factor for PSD (28), the degree of hirsutism was not compared between cohorts as this information was not reliably documented in a fashion enabling this. This study compared a single PEF technique to LFP techniques that were not the same for all patients. Whilst this may influence direct comparison, the various LFP techniques have been shown to perform similarly [6, 14, 15].
Covering a span of nearly 14 years, this study is the largest paediatric-focussed cohort utilising fibrin glue to manage PSD with the longest follow-up, to the best of our knowledge [6, 8, 9, 27, 29, 30]. We have demonstrated clinically relevant decreases in symptom recurrence alongside significantly decreased rates of complications and further surgical intervention using fibrin glue techniques, compared to traditional LFP techniques. We believe LFP in the paediatric population should be saved for severe or refractory disease, when minimally invasive treatment of recurrent PSD is felt to be inappropriate or fails.