In examining treatment of colon cancer patients who underwent colectomy at 1296 hospitals using data from the NCDB, we found that although the proportion of compliant hospitals (those that examined at least 12 lymph nodes in at least 75% of patients) increased considerably from 1996–1997 to 2004–2005, the majority of hospitals failed to comply with the 12-node measure. To our knowledge, this is the first study to examine the 12-node measure at the hospital level and provide a hospital report card for regional lymph node evaluation for colon cancer in the United States.
Prior studies conducted at the level of individual patients have demonstrated that only approximately 37% to 50% of colon cancer patients in the United States have 12 or more nodes examined (21
). At the hospital level, we found that the overall performance rate (proportion of patients at a hospital who had at least 12 nodes examined) increased by a statistically significant extent from 1996–1997 to 2004–2005. This increase was observed regardless of hospital type or volume. This improvement is presumably due to multiple factors that have increased awareness of the importance of lymph node examination for colon cancer. Nodal evaluation is likely to improve further with the recent development of a 12-node measure by multiple national oncology organizations and as physicians and hospitals recognize that a requirement to examine 12 or more nodes may affect referral and reimbursement.
The primary objective of this study was to determine the number of hospitals that are compliant with the 12-node measure. We considered a hospital statistically compliant if the upper limit of the 95% CI for the estimate of its performance was greater than or equal to 75% to preclude categorizing hospitals as noncompliant simply based on statistical variation. The percentage of statistically compliant hospitals increased from 15.0% in 1996–1997 to 38.9% in 2004–2005. Overall, national compliance with a 12-node measure remains low, possibly because some question whether the 12-node measure is important for staging and is an indicator of hospital quality. However, the increase in performance over time, particularly at NCI–CCCs, is encouraging and demonstrates that improved compliance with the 12-node measure is feasible.
In examining the association of hospital factors with compliance with the 12-node measure, we found that the rate of statistical compliance for NCI–CCCs (78%) was higher than that for other hospital types. Previous studies have shown that colon cancer patients treated at high-volume specialized cancer centers have better long-term outcomes (eg, recurrence and survival) than those treated at low-volume community hospitals (35
). Better lymph node examination rates at NCI–CCCs and other academic hospitals may in part explain this disparity.
Because hospitals care for varying proportions of elderly patients and those with left-sided tumors, both of which are associated with lower nodal counts, it has been suggested (37
) that a 12-node measure that compares hospitals must adjust for differences in the patient populations at various hospitals and hospital types. To examine the effect of patient characteristics on the rate of lymph node examination, the predicted rates were calculated as a function of the multivariable logistic regression model. We found that patient characteristics did not affect the proportion of hospitals meeting the compliance benchmark. Thus, these differences among hospitals do not appreciably affect evaluation of compliance rates, and comparing hospitals without adjustment for case mix is likely appropriate. Moreover, adjustment for differences in patient populations is, in principle, not needed for process measures, because adherence with the measure is either met or not met.
The large number of hospitals in the United States that are not compliant with the 12-node measure may indicate to some that 12 lymph nodes is not an appropriate threshold for a quality indicator for colon cancer because it is either not attainable or unimportant. The rate of adherence with a requirement to evaluate 12 regional lymph nodes is dependent on the extent of surgical resection, the thoroughness of pathological examination, and multiple patient factors (38
). However, large institutions and entire geographic areas have been able to dramatically improve nodal examination rates for colon cancer. In a study of eight NCCN hospitals, Rajput et al. (41
) found that during 2005–2006, 89% of colectomy patients had 12 or more nodes examined. Similarly, emphasizing the importance of nodal evaluation has resulted in a substantial improvement in lymph node examination in the Canadian province of Ontario (42
). If large institutions or an entire province can improve lymph node examination rates, then it is likely that evaluation of 12 nodes is a reasonable benchmark for colon cancer, and increasing awareness of the importance of nodal evaluation through multidisciplinary initiatives can improve lymph node examination for colon cancer.
Hospital-specific performance for the 12-node measure will be reported to all 1450 individual facilities currently reporting to the NCDB. The reporting process is meant to increase awareness of the importance of adequate nodal evaluation and allow institutions to privately compare their performance with a large national sample of hospitals. Hospitals with outlying nodal evaluation rates can be identified and notified so that these centers can initiate internal quality improvement initiatives.
The potential limitations of this study should be noted. First, there is considerable statistical variation in 12-node measure performance rates among extremely low-volume hospitals, and an argument could be made to exclude hospitals that performed a small number of colectomies per year. However, when we excluded very low–volume hospitals, the proportion of compliant hospitals did not change substantially (data not shown). Second, only hospitals approved by the CoC report to the NCDB. These hospitals may exhibit a higher level of specialization than institutions that are not approved by the CoC. Thus, if all hospitals in the United States were examined, the differences in 12-node measure compliance between NCI–CCCs and community hospitals would likely be augmented. Finally, the benchmark for compliance of 75% was derived statistically by calculating the mean performance rate of hospitals in the top quartile of lymph node examination rates in 2004–2005. Some have suggested that the quality threshold should be the performance rate of the hospitals in the 90th percentile (43
). Although there are numerous methods to derive quality benchmarks, 75% serves as a statistically derived, conservative, and achievable starting point. Establishment of a benchmark should be considered an iterative process as hospitals improve and science progresses.
This study presents a hospital report card for regional lymph node examination for colon cancer in the United States. Nearly two-thirds of hospitals failed to meet the benchmark for compliance with the measure in 2004–2005. Considerable improvement in lymph node examination rates is needed, irrespective of hospital type. The measure may be used to assess physicians and/or hospital performance in the future, and a surveillance period will allow hospitals to focus on the issue and improve their performance before they may be held accountable. The 12-node measure offers an opportunity to improve the quality of care for colon cancer patients in the United States.