How Does Surgeon and Hospital Volume Affect Patient Outcome after Traumatic Injury?

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Chapter 48 How Does Surgeon and Hospital Volume Affect Patient Outcome after Traumatic Injury?

For many orthopedic conditions, a clear association exists between patient outcome and the volume of similar cases treated by the hospital or surgeon providing care in Canada,¹^–⁴ the United States,⁵^–¹² and other countries.¹³^–¹⁵ After traumatic injury, patient factors such as age, comorbidity, and the severity of injury are by far the most important determinants of mortality, although provider volume and availability of appropriate resources and care protocols do have an important influence on survival. For survivors of multisystem injuries, functional outcome is in large part determined by the residual impact of musculoskeletal and neurologic injuries. The experience and expertise of the hospital and the surgical team managing such injuries may well have a profound impact on the risk for complications, the rate of return to maximal function, the cost of care, and the ultimate functional outcome achieved. Provider experience may affect not only the excellence of procedural execution, but may be a factor at all stages of management, including preoperative decision making, the availability of optimal implants, monitoring equipment and support staff, and the adherence to optimized postoperative management protocols. Few studies have attempted to delineate the underlying mechanisms that might be driving the volume–outcome relation.² Although the mechanism may be that high-volume providers have developed mature systems of care and expertise from exposure to a high volume of cases, there is also some evidence that vulnerable populations in the United States with elective conditions such as total knee replacement are preferentially selecting or being forced to select low-volume institutions.¹⁶ A similar finding was noted for patients with hip fracture.¹⁷

OPTIONS

The demonstration of a systematic variation in patient outcome should be followed by strategies to eliminate suboptimal results, thereby minimizing outcome variation near the high end of the scale. Strategies to achieve this fall into three categories: (1) mandating minimum provider volumes; (2) regionalizing care to specialized centers; and (3) trying to understand the internal mechanisms involved and providing support, education, and best practice advice to those with inferior results (regardless of whether that given provider is low or high volume). The problem with simply mandating a minimum volume for a provider is that there is no scientific evidence to support the existence of a threshold volume below which outcomes are likely to suffer.^14,¹⁸ Furthermore, a given lowvolume provider might have excellent results, and a specific high-volume provider could have a high complication rate. Alternative strategies may include monitoring provider outcomes and following up on significant variances (in a negative or positive direction) to learn from good results and to work to improve poor results. Regionalization for specific conditions to specialized high-volume “centers of excellence” has been proposed for a number of conditions including trauma⁷ and total joint arthroplasty.¹⁹ Regionalization allows for a critical mass of specialists with access to specialized equipment, care protocols, and a variety of medical and support staff available to support the care of resource-intensive, specific conditions; but for co-mmon conditions that require no specialized staff or equipment, the inconvenience and expense of patient travel needs to be considered. If a volume–outcome relation were demonstrated for a less resource-intensive injury, an alternative strategy to regionalization for such conditions might involve linking low- and high-volume providers together to share in preoperative surgical decision making, provide advice regarding the development of care protocols for perioperative care, and to monitor the execution of surgery itself.

The purpose of this chapter is to determine whether a volume–outcome relation exists for traumatic orthopedic conditions, with the aim of assisting clinicians and policy makers in developing strategies to improve patient outcomes, and helping researchers to strengthen the evidence base used to refine these strategies.

EVIDENCE

Specialized hospitals and surgeons have specific qualifications and interest in the subject of their subspecialty area. They also tend to be high-volume providers for the conditions of interest. Both specialized trauma providers and total joint arthroplasty centers have been studied.

Specialized Hospitals

In a Level I prospective cohort study, MacKenzie and colleagues ⁷ compared patient outcomes for those treated in specialized trauma hospitals versus nontrauma hospitals. The most severely injured complex patients (with one or more system Abbreviated Injury Scale scores of 5 or 6) were significantly more likely to survive when treated in specialized trauma centers (RR of hospital death, 0.70; 95% confidence interval [CI], 0.51–0.96). Young trauma victims younger than 55 years also had a lower in-hospital mortality rate when treated in specialized trauma centers (RR, 0.66; 95% CI, 0.48–0.89). For older patients, the mortality rate was driven largely by comorbidity and age with less noticeable influence on risk for death for specialized versus nonspecialized trauma center care. These findings are consistent with data from the United Kingdom. Freeman and coauthors¹³ (Level II) note that the relation between volume and outcome for trauma centers in the United Kingdom was significant only for patients with complex multiple traumatic injuries; however, even the highest volume trauma hospital studied had volumes of only 96 patients per year, which is well below the volumes seen in many North American centers.^7,^{11, 20}

Specialized centers for total joint surgery have also been evaluated. Cram and coauthors ¹⁹ (Level II) compared total joint replacement surgery in specialty and general hospitals using Medicare data from 1999 to 2003, which included 51,788 total hip and 99,765 total knee replacements. The profile of patients treated at specialized centers differed from that of general hospitals. Patients attending specialized centers tended to be from wealthier neighborhoods and had fewer comorbid conditions. After adjusting for patient comorbidity and hospital volume, the risk for adverse events was lower in specialty hospitals (odds ratio [OR], 0.64; 95% CI, 0.56–0.75) for primaries and much lower for more complex revision operations (OR, 0.49; 95% CI, 0.36–0.66).