The STP, Death by Bedsheets & Cheese.
What do the creation of NHS ‘specialist centres’, cheese, and death by entanglement in bedsheets have in common? Not much really, but there’s a 94% correlation between the increase in per capita cheese consumption in the US & the rise in number of deaths from becoming entangled in bedsheets, and there’s a 70-80% correlation between larger hospital volumes and better patient outcomes, according to Mid & South Essex STP.
The point is, that ‘correlation’ does not mean ’cause’.
Two of the biggest scientific studies that the STP has used [Halm 2002, Chowdhury 2007] to back up its proposals to centralise services from Southend, Basildon and Broomfield both make it clear that simply making a centre larger will not make the outcomes for patients better. Larger centres show better results for some procedures, but it’s not because they’re larger.
In one of the NHS’s own reports it says:
“There is still only limited evidence to suggest that the observed associations are causal, and that interventions to manipulate volume can lead to better outcomes. It is, however, very important to note that the issue here is that evidence is sparse, rather than there being strong evidence of a lack of a causal association. The relevance of the observed volume/outcome relationships to health service planning depends crucially on how one interprets the underlying mechanisms which generate the associations.” [http://www.sehd.scot.nhs.uk/nationalframework/Documents/VolumeOutcomeReportWebsite.pdf]
To simply use this research to support plans to centralise services is plain wrong. There is no consensus on what high or low volume is either. One study may quote a figure of 20 instances per year of a certain medical operation as being ‘high’, whilst another study uses the figure of 20 as ‘low’.
The majority of data used in these studies is from the 1980s and 90s, with some from the 70s and the oldest paper quoted being published in 1957. It’s fair to say that medical procedures have come on significantly in this time and, possibly more importantly, how these advances are more rapidly and better communicated throughout the medical profession has taken a quantum leap – the internet wasn’t around when a lot of these studies were undertaken.
The systematic review by Halm, 2002, looked at 135 papers relating to hospital volume/outcome, and here are some of the observations that the STP aren’t printing in their literature or on their website:
“The magnitude of the volume–outcome association varied greatly by topic. We found the most consistent and striking differences in mortality rates between high- and low-volume providers for several high-risk procedures and conditions, including pancreatic cancer, oesophageal cancer, abdominal aortic aneurysms, paediatric cardiac problems, and treatment of AIDS. The magnitude of volume– outcome relationships for more common procedures, such as CABG, coronary angioplasty, and carotid endarterectomy, for which selective referral and regionalization policies have been proposed, was much more modest. This was true even after we took the lower average mortality rates for these procedures into account.
Because most of the studies we reviewed were based on data from the 1980s to mid-1990s, the extent to which their findings reflect current practice and volume is unclear.
Missing from most of the research we reviewed was an exploration of the mechanism through which volume influences outcomes. Volume is clearly a proxy measure of other things because it cannot directly produce good or bad results. Specific processes of care, correlated with volume, are the most likely explanatory factors.
It is important to emphasize that any relationship between volume and outcome is true only on average. Outcomes vary widely among individual hospitals and physicians. Some low-volume providers have good outcomes, and some high-volume providers have poor outcomes.
Twenty years of research have established that, for some procedures and conditions, higher volume among hospitals and physicians is associated with better outcomes. However, the magnitude of the relationship varies greatly among individual procedures and conditions. The clinical and policy significance of this finding is complicated by methodologic shortcomings of many studies. Even when a significant association exists, volume does not predict outcome well for individual hospitals or physicians. Investigating precisely what physicians and hospitals with high volumes and good outcomes do differently from those with low volume and poor outcomes is likely to contribute substantially to our knowledge.”
The other large systematic study by Chowdhury, 2007, had many of the same observations plus this rather interesting caveat of why hospitals with larger volumes may show better results when analysing retrospective studies was:
“.. hospitals that transfer patients after primary surgery back to a referring (often smaller and lower volume) hospital may have better outcomes because patients who develop complications or die are more likely to do so in the referring institution. Length of hospital stay will also appear shorter than in hospitals that retain their own patients after primary surgery until discharge home. This interhospital transfer is common and may bias outcomes in favour of certain hospitals, typically high-volume referral centres. Retrospective studies that usually provide only data collected during the patients’ stay in the operative hospital are unlikely to unmask these inaccuracies. The smaller but more reliable sample of prospective studies demonstrated that when this and other potential inaccuracies are minimized, the benefit from high hospital volume is limited; high surgeon volume was still beneficial.”
There is no doubt that Mid & South Essex STP have been highly selective in which parts of this research they’ve chosen to use to back up their case and in doing so have obviously not necessarily had the best interests of patients at heart.
The limited scope of this ‘evidence’, taken in conjunction with the very dubious , vague and potentially dangerous plans for patient transport, do not support a reorganisation that will ultimately lead to the loss of a General Hospital, as we know it, in Southend.
Chowdhury, M. M., Dagash, H., & Pierro, A. (2007). A systematic review of the impact of volume of surgery and specialization on patient outcome. British journal of surgery, 94(2), 145-161.
Halm, E. A. et al. (2002) Is volume related to outcome in health care? A systematic review and methodologic critique of the literature. Annals of internal medicine, 137(6), 511-520.
Mid & South Essex STP Clinical Evidence Pack:
*Data sources: U.S. Department of Agriculture and Centers for Disease Control & Prevention