Introduction
More than 10 million surgical operations are conducted every year in the NHS, with the majority of these involving a wound created by surgical incision.1 Most incised surgical wounds heal by primary intention, when the wound edges are closely apposed and sutured, clipped or glued together. However, not all surgical wounds heal in this way; some wounds are left open after surgery and heal from the bottom up by the formation of granulation tissue (known as healing by secondary intention). The surgical wounds healing by secondary intention (SWHSIs) may be planned (e.g. after significant tissue loss for which primary closure is not possible, or in the presence of infection). Alternatively, healing by secondary intention may be unplanned when a primarily closed wound opens or ‘dehisces’ (full or partial separation of wound edges). These SWHSIs, also called ‘open surgical wounds’, may remain open for many months, are prone to infection, may prolong hospital stays, and necessitate further hospital admissions and surgeries (delayed primary closure) or skin grafting,2 all adversely affecting patients’ quality of life and incurring substantial NHS costs.
Prevalence of SWHSIs
Although SWHSIs are thought to be relatively common, when we planned this research there were few national or international data regarding their epidemiology. Two published studies estimated that SWHSIs constituted approximately 28% of all prevalent surgical wounds.3,4 From data collected in Hull and East Yorkshire, UK, Srinivasaiah et al.4 reported 136 open surgical wounds and 74 dehisced surgical wounds, from a total population of 590,000 (a point prevalence of 0.36/1000 population). Further UK cross-sectional data from Bradford, UK, reported 111 wounds that were classed by the study authors as open surgical wounds and a further 88 that were classed by the study authors as having broken down post surgery.3 However, the size of the underlying population and, hence, point prevalence for these wounds was not reported. A population-based estimate of the prevalence of SWHSIs alongside in-depth investigation of their origin, natural history, typical treatments and impact on patients and health services was needed.
Details of patient and wound characteristics
Previous research on wound prevalence by Vowden and Vowden3 and Srinivasaiah et al.4 focused on all wounds, rather than specific wound types. To the best of our knowledge, when we began this research, there was no high-quality information (national or international) describing patients with a SWHSI (age, sex, comorbidities, concomitant medications, surgical speciality); wound characteristics (site, size location, aetiology, whether or not the wounds were planned to be left open before surgery, frequency of wound infection); SWHSI treatments or healing rates in general and for specific patient groups (e.g. those with diabetes mellitus). Robust time to healing data were also limited and reports frequently presented inaccurately analysed data.5–10 The generalisability of the existing research was also limited, as many trials reported time to healing rates in relation to subpopulations of SWHSI patients and treatments: one trial5 of perineal wounds and foam dressing, two trials7,8 of pilonidal sinus wounds and silastic foam dressing, and one trial10 of below-knee amputation wounds and plaster cast with silicone sleeve or elastic compression. The lack of systematic data describing SWHSIs and their treatment and outcomes was matched by a lack of knowledge about the impact of SWHSIs on patients’ quality of life or daily functioning, as well as the impact of these wounds on the use of health-care resources. This, in combination, made it almost impossible to assess the impact of SWHSIs and their treatments on patients, or to plan new research studies to assess the clinical effectiveness and cost-effectiveness of potential new or alternative treatments or interventions.
The treatment of SWHSIs
Management of SWHSIs often involves daily or more frequent dressing changes, sometimes with packing of the wound cavity. Many different dressing options are available, from simple dressings such as gauze (which can be painful to remove) to more modern options such as foam, hydrocolloid and alginate dressings. Wounds may also be treated by debridement (the removal of foreign material and devitalised tissue) or by skin grafting. When this research was conceived, the type and frequency of treatments being used for SWHSIs was not known. Randomised controlled trials (RCTs) in SWHSI patients are infrequent and often poorly designed, underpowered, utilise surrogate outcomes and often report limited or incorrectly analysed healing data, making interpretation of these data incredibly difficult. For example, a multicentre RCT comparing the effects of zinc oxide with placebo mesh on secondary-healing pilonidal wounds was underpowered, recruiting only 64 participants (n = 33 zinc and n = 31 placebo), and although it did not detect a difference in median healing times (54 days, interquartile range 42–71 days for zinc; 62 days, interquartile range 55–82 days for placebo; p = 0.32), this may have been due to the lack of power. In the same study, fewer postoperative antibiotics (a surrogate marker of wound infection) were prescribed in the zinc oxide group (n = 3) than in the placebo group (n = 12) (p = 0.005).11
In terms of evidence of effectiveness of different treatment options, Vermeulen et al.12 explored the relative effects of dressings and topical agents for SWHSIs in a systematic review. They found only 13 RCTs, all of which were small, of poor quality and often conducted > 10 years previously. There was no evidence to indicate that the choice of dressing or topical treatment offered any benefit in terms of wound healing time, but the data were sparse. A systematic review, conducted to inform National Institute for Health and Care Excellence (NICE) clinical guidelines on surgical site infection, investigated the effects of topical antiseptics and antibiotics (including impregnated dressings) on the risk of wound infection in SWHSIs.13 The four included studies were small and provided generally uncertain evidence on a range of uncommon treatment options. The guidelines recommend that chlorinated lime and boric acid [Edinburgh University Solution of Lime (EUSOL)] and gauze, moist cotton gauze or mercuric antiseptic solutions should not be used to prevent surgical site infection in the management of SWHSIs.13
Increasingly, more advanced and costly wound treatments have been extensively adopted into clinical practice, with inadequate supporting evidence. One example is negative-pressure wound therapy (NPWT), a device that applies a carefully controlled negative pressure (or vacuum) to the dressing, moving tissue fluid away from the treated wound area into a disposable canister.14 The canister is removed and replaced either when it becomes full or at least once per week. The device is generally used as part of the SWHSI treatment pathway, rather than to the point of healing, and can be administered and removed by both nurses and surgeons.
Cost of treating SWHSIs
Surgical wounds healing by secondary intention can be large and may produce a significant volume of exudate, which can be difficult to manage, and frequent, time-consuming, dressing changes are common. In addition, SWHSIs must also be protected from infection and trauma during healing. It has been suggested that SWHSIs are at high risk of postoperative infection, with the wound providing an ideal environment for bacterial proliferation, which may be associated with delayed healing.15 These factors, and the possible need for further surgery, suggest that the costs of treating patients with SWHSIs could be substantial. The lack of available epidemiological evidence in relation to SWHSIs had, however, made it difficult to ascertain the health and social care costs of treating these wounds.
SWHSIs: the patients’ perspective
The lack of systematic data describing SWHSIs, their treatment and outcomes was matched by a scarcity of knowledge about the impact of SWHSIs on patients’ quality of life. Little was known regarding patients’ perspectives and experiences of living with a SWHSI, or their views, expectations and concerns regarding management and outcomes.
SWHSIs: the clinicians’ perspective
A variety of clinicians, including surgeons, tissue viability nurses and general practice nurses, are all commonly involved in the management of patients with SWHSIs. As previously stated, there is a dearth of high-level evidence to guide the management of these patients, particularly regarding the clinical effectiveness and cost-effectiveness of different treatments or interventions. Greater clarity is required regarding assessment of these wounds and the factors that influence management decisions.
Summary
In summary, this research programme was undertaken recognising that SWHSIs may be common and costly but that there was a need for further exploration of the extent, nature, outcomes and impact of these wounds. The lack of international epidemiological data regarding these patients seriously impairs the development of new research studies in this area. There was also huge uncertainty regarding SWHSI management. Options ranged from inexpensive simple dressings to the more complex and costly NPWT, but accurate data regarding the frequency of use of specific treatments was non-existent. In addition, all treatment options for SWHSIs lacked robust, supportive evidence bases in terms of clinical effectiveness and cost-effectiveness, and the impact on patients’ quality of life. As a result, clinicians and patients were uninformed about how to care for SWHSIs and, specifically, which treatment options were most effective and offered the best value for money. The need for research to fill these evidence gaps was also highlighted by the NICE guidance.13
Given the number of treatment options available, it is important that patients, carers and health professionals are involved in trial design, including the selection of significant outcome measures, and that research is conducted through sufficiently powered trials to detect significant differences in healing rates between treatments. However, the enormous cost of conducting the trials required to fill the evidence gaps means that a rush to undertake such studies, before obtaining additional key intelligence, would be hugely inefficient. There were several important unknowns: information about the natural history and epidemiology of SWHSIs; which treatments were being used most commonly and, thus, should be evaluated; whether or not the decision uncertainty associated with various treatments justifies an expensive trial; and whether or not a trial is feasible. In addition, little was known about which outcomes matter to patients with SWHSIs and what the desirable treatment characteristics are from the perspective of the staff treating them. We have undertaken research to generate vital data regarding an important, costly and hugely under-researched health problem. The research findings will aid in planning service delivery and future research, including economic modelling and primary studies.