Thromboprophylaxis following hip and knee arthroplasty

Hip and knee arthroplasty are increasingly common surgical procedures in Australia, with more than 85,000 expected to be performed this year. Compared to the general public, people who undergo a hip or knee arthroplasty are at an increased risk of developing blood clots (also known as a venous thromboemboli or VTE) as both procedures activate all three aspects of Virchow's risk triad during the pre-, peri- and postoperative period. Importantly, VTE are considered one of the most common causes of preventable death in Australian hospitals. Whilst there are mechanical and pharmacological measures that can be employed to prevent VTE (known collectively as thromboprophylaxis), and many national and international bodies have released thromboprophylaxis guidelines over the years, previous studies have reported consistent underutilisation of thromboprophylaxis both in Australia and overseas. The overarching objective of this thesis was to examine thromboprophylaxis prescribing patterns in Australia, and the factors that influence them. To achieve this aim, a number of complementary studies were conducted, including both qualitative and quantitative work. Retrospective reviews were conducted at six hospitals across three states to explore prescribing patterns; the results indicated that while anticoagulant thromboprophylaxis is routinely used in hospital, its continuation at discharge is not habitual ‚Äö- despite recommendations by contemporary guidelines to extend therapy usually beyond the inpatient period. Interestingly, prescribing patterns were generally found to be more aligned with recent contemporary recommendations than recommendations existent at the time of prescribing, indicating practice preceded guidelines. A survey exploring hospital protocols and local prescribing practices identified that only 50% of the 143 Australian hospitals surveyed had thromboprophylaxis protocols and that their alignment with published literature varied considerably. Surprisingly, private hospitals tended to base their guidelines on the National Health and Medical Research Council (NHMRC) Guideline, whereas public hospitals were more likely to favour individual or collective surgeon preferences. Where they existed, adherence to hospital protocols was apparently high (86%), and predictably trended to increase in hospitals with adherence strategies in place (91% vs. 79%). Two online surveys were conducted with orthopaedic surgeons practising in Australia. Whilst the first survey was limited by its small number of respondents (25), it identified that individual prescribing preferences vary significantly, with many surgeons perceiving guideline recommendations (including those of the NHMRC Guideline) as inappropriate. Although few respondents believed that pharmacological prophylaxis prevents fatal pulmonary emboli, and many responded that VTE risk is low following arthroplasty, all participants routinely prescribed pharmacological prophylaxis postoperatively. In addition to bleeding concerns and a perceived low VTE risk, the third strongest barrier to thromboprophylaxis use was the belief that study evidence is not applicable to real-world inpatient populations. Along this line, a number of surgeons expressed suspicions that industry funding was heavily biasing guideline recommendations, either directly by sponsoring guideline authors or indirectly by sponsoring associated research. The second survey had a significantly larger number of respondents (221), and maintained the results of the first study. Semi-structured interviews were used to explore surgeons' preferences, opinions and experiences in greater detail. Moreover, to complement these views and to gain a better understanding of real practice, these interviews were supplemented by interviews with Tasmanian based orthopaedic interns, general practitioners (GPs) and clinical pharmacists. While a surgeon's opinion was identified to be greatly moulded by their training and collective experience, and not by contemporary guidelines, other health professionals' opinion were more inclined to be shaped by guidelines. The interviews also identified that even though participants differed in their thromboprophylaxis preferences and opinions, they all strongly agreed that thromboprophylaxis should be tailored to the individual patient. All surgeons expressed familiarity with at least one contemporary guideline; however, other health professionals generally did not. This lack of knowledge and familiarity naturally impairs their ability to contribute to postoperative care. Additionally, hospital to community communication was described as slow and unreliable by participants, further disadvantaging GPs from being able to effectively contribute to VTE prevention after discharge. Rather than awaiting the formulation of a Tasmanian based protocol (which was attempted by an outside group early on in the research), another strategy to optimise thromboprophylaxis use would be to instigate a statewide strategy to increase the uptake of the NHMRC Guideline. One of the biggest barriers identified in this research to the adoption of guidelines such as the NHMRC Guideline is the perception that they impose a 'one size fits all' approach to thromboprophylaxis by making 'carte blanche recommendations'. In reality, the NHMRC Guideline takes a comprehensive approach to VTE prophylaxis and, unbeknown to many health professionals, actually addresses the many concerns they expressed in the studies in this thesis. A quick ready-reference tool developed from the NHMRC Guideline could assist greatly in overcoming communication and knowledge obstacles described in this thesis; and a suggestion of what this ready-reference tool could look like is included. Passively disseminating clinical practice guidelines has been ineffective at optimising thromboprophylaxis use to date, both in Tasmania and interstate, potentially leaving many patients exposed to a higher risk of VTE. A clear understanding of the factors that influence thromboprophylaxis prescribing and guideline adoption is essential. Together, the studies contained in this thesis identified many barriers to thromboprophylaxis use and guideline adoption, including: concerns over bleeding complications (and associated potential underreporting), the scope of industry influence, and the threat of guidelines being too prescriptive, threatening professional autonomy and thereby posing a potential medico-legal liability to surgeons. These barriers should be addressed in forthcoming editions of the NHMRC Guideline to encourage uptake of its recommendations and ensure optimal outcomes for patients.