Professor Nick Graves is a leading health economist. He has done some fantastic work in the area of infection prevention and control and has an interest in improving health services. I invited Nick to write a blog and he hasn’t disappointed with a blog to stimulate debate and discussion. @
Thanks for the blog Nick – Brett
The notion that scarce health care resources are used to fund technologies and clinical services that harm patients is difficult. Common sense tells us this would never happen. Yet up to 1/3 of all spending in the US is on medical spending for services that do not improve health (1), and evidence that Australia pays for low value or even harmful care is emerging (2, 3).
That fact we do this as part of infection prevention practice is a worry. The community prides itself on improving safety and saving costs, rather than the opposite. The culprit is the continued use of laminar air flow in operating rooms.
In 1969 Charnley and Eftekhar published evidence for reduced numbers of airborne bacterial counts and lower rates of sepsis when laminar air flow was used (4), and in 1978 Lowbury and Lidwell published the findings of a multi-centre randomised trial that showed the incidence rate of joint sepsis was 50% lower in patients that had surgery in an ultraclean environment (5). The Achilles heal of the randomised study was that antibiotic prophylaxis was not included in the analysis, and this might confound the finding about laminar air. Since this study, evidence against laminar air flow has emerged from Germany (6), New Zealand (7), the US (8) and Norway (9). All these data were synthesised in a meta-analysis that provides effectiveness estimates for a wide range of infection prevention bundles for joint replacement (10). It showed that adding laminar airflow to systemic antibiotics and antibiotic-impregnated cement, when compared to conventional ventilation attracted an odds ratio of 1.96 (95% CI 0.52-5.37). So laminar airflow increases risk of infection in joint replacement. And before you worry about statistical significance, remember that a p-value of 0.05 is arbitrary and tells us nothing useful about whether laminar air flow should be part of health services (11, 12).
A decision to continue to use laminar air flow and the impact this has for health services was shown by a recent HTA report completed for the NHS (13).
An extra 260 patients will suffer a deep infection each year. Treating them will require 127 extra one stage revisions, an extra 150 DAIR procedures (debridement, antibiotics, irrigation, and retention) and 50 extra two stage revisions. This will cost the NHS £5,053,528 in treatment and services and patient health outcomes will of course be worse. A study for Australia (14) showed that continuing with laminar air flow could result in an extra 179 cases, increased costs of $4,592,200AUD and four extra deaths.
There are likely to be many reasons why this practice is not stopped: making a change is risky for altruistic individuals, and I cannot think of anyone who would really want to blow this whistle; the evidence for a making a change can be poked for holes by supporters of laminar airflow; patients are poorly informed and cannot adequately express their preference for safety. This problem is common among health services, and this is one example.
- Fisher ES, McClellan MB, Bertko J, Lieberman SM, Lee JJ, Lewis JL, et al. Fostering accountable health care: moving forward in medicare. Health Aff (Millwood). 2009;28(2):w219-31.
- Elshaug AG. Over 150 potentially low-value health care practices: an Australian study. Reply. Med J Aust. 2013;198(11):597-8.
- Runciman WB, Hunt TD, Hannaford NA, Hibbert PD, Westbrook JI, Coiera EW, et al. CareTrack: assessing the appropriateness of health care delivery in Australia. Med J Aust. 2012;197(2):100-5.
- Charnley J, Eftekhar N. Postoperative infection in total prosthetic replacement arthroplasty of the hip-joint. With special reference to the bacterial content of the air of the operating room. Br J Surg. 1969;56(9):641-9.
- Lowbury EJ, Lidwell OM. Multi-hospital trial on the use of ultraclean air systems in orthopaedic operating rooms to reduce infection: preliminary communication. J R Soc Med. 1978;71(11):800-6.
- Brandt C, Hott U, Sohr D, Daschner F, Gastmeier P, Ruden H. Operating room ventilation with laminar airflow shows no protective effect on the surgical site infection rate in orthopedic and abdominal surgery. Annals of surgery. 2008;248(5):695-700.
- Hooper GJ, Rothwell AG, Frampton C, Wyatt MC. Does the use of laminar flow and space suits reduce early deep infection after total hip and knee replacement?: the ten-year results of the New Zealand Joint Registry. The Journal of bone and joint surgery British volume. 2011;93(1):85-90.
- Miner AL, Losina E, Katz JN, Fossel AH, Platt R. Deep infection after total knee replacement: impact of laminar airflow systems and body exhaust suits in the modern operating room. Infect Control Hosp Epidemiol. 2007;28(2):222-6.
- Engesaeter LB, Lie SA, Espehaug B, Furnes O, Vollset SE, Havelin LI. Antibiotic prophylaxis in total hip arthroplasty: effects of antibiotic prophylaxis systemically and in bone cement on the revision rate of 22,170 primary hip replacements followed 0-14 years in the Norwegian Arthroplasty Register. Acta orthopaedica Scandinavica. 2003;74(6):644-51.
- Zheng H, Barnett AG, Merollini K, Sutton A, Cooper N, Berendt T, et al. Control strategies to prevent total hip replacement-related infections: a systematic review and mixed treatment comparison. BMJ Open. 2014;4(3):e003978.
- Claxton K. The irrelevance of inference: a decision-making approach to the stochastic evaluation of health care technologies. J Health Econ. 1999;18(3):341-64.
- Goodman SN. Toward evidence-based medical statistics. 1: The P value fallacy. Ann Intern Med. 1999;130(12):995-1004.
- Graves N, Wloch C, Wilson J, Barnett A, Sutton A, Cooper N, et al. A cost-effectiveness modelling study of strategies to reduce risk of infection following primary hip replacement based on a systematic review. Health Technol Assess. 2016;20(54):1-144.
- Merollini KM, Crawford RW, Whitehouse SL, Graves N. Surgical site infection prevention following total hip arthroplasty in Australia: a cost-effectiveness analysis. Am J Infect Control. 2013;41(9):803-9.