Our results indicate that there is variation within the VA health system regarding the time from initial clinical event until the diagnosis of CRC. Predictors of a longer period until diagnosis were older age, the presence of comorbidities, and geographic region.
A single VA facility study examining medical system delay from the view point of missed opportunities (symptoms, signs, abnormal tests) that should have prompted an endoscopic evaluation for cancer, found that age > 75 years, coronary artery disease, and congestive heart failure were associated with a higher likelihood of a missed opportunity. The missed opportunities, in turn, were often associated with dramatically longer lag times until endoscopic referral [14
]. These results are consistent with this study’s findings of increased time to diagnosis for older patients and those with comorbidities. The other medical problems of, particularly, older patients could distract physicians from investigating GI symptoms or abnormal tests. Physicians could be hesitant to refer older patients to colonoscopy because of the higher complication rate in this population or could be biased against treating the elderly more generally. Alternatively, older patients and those with comorbidities could be more likely to become acutely ill and require cancelling and rescheduling of tests or procedures. The retrospective design of both studies is not able to distinguish among these possibilities.
We found regional differences in making a timely CRC diagnosis. The different results among the prior single center VA studies could, in part, reflect regional differences. Whether a shorter time to diagnosis reflects more efficient ordering of tests and consults or more readily available resources to carry out those orders is unknown. By the global resource measure of complexity level, all of the sites were roughly equivalent. It is likely, however, that local resources and the local balance of supply and demand for specific services relevant to CRC diagnosis do differ across regions and individual facilities. Some regional variation in time to diagnosis may be acceptable because stage at diagnosis was not associated with time in the medical system until diagnosis. This does not, however, account for other outcomes such as patient satisfaction.
As noted earlier, research results have been inconsistent regarding the presence and, if present, direction of an association between delay and cancer stage or survival [2
]. Differences in results may be related to differences in study design and setting. Even within the VA healthcare system one single center study found that a longer time from colonoscopy referral (for abnormal tests, symptoms or family history) to endoscopic diagnosis of CRC was associated with a less advanced cancer stage and decreased mortality [3
] while another single center study found that a longer time from positive FOBT until colonoscopy was associated with increased risk of finding neoplasia on endoscopy [15
]. The average time to endoscopy was 41 days in the first and 236 days in the second Design differences between the studies that likely contributed to the different results included that one began with patients who had a diagnosis of colorectal cancer and searched backwards in the medical record examining referral to colonoscopy for a variety of indications [3
] while the other began with consecutive patients with a positive FOBT and followed them forward in the medical record [15
)]. Both of those centers participated in VA CanCORS. The range of delay observed in our study is unlikely to result in a shift in stage given the natural history of CRC; however, that may not be the only outcome of interest to patients and providers.
Our results have implications for VA and non-VA populations. Our findings support the equity of the VA system with respect to race and colorectal cancer detection. Regional differences in health care spending and resource allocations have been previously documented using Medicare data [16
]. We anticipated that geographic differences would be attenuated in the VA system because of its centralized structure, but local resources likely play a large role. The potential barriers to a timely diagnosis for older patients are not necessarily a reflection of the VA system, but likely an issue in non-VA populations as well. Finally, the finding that screen-detected cancers are more likely to be early stage confirms the real world effectiveness found in the trials and studies of screening efficacy.
Our study has several strengths. The study includes a large sample of patients from 15 VA medical centers whereas prior VA studies were conducted in a single center. The chart abstraction used standardized protocols to collect data from a comprehensive, linked electronic medical record that included primary and subspecialty care at any VA facility and provided clinical details not available in administrative data sets. The cancer diagnoses were confirmed with histology unlike some studies which used tumor size as a proxy for malignancy.
There are also limitations of this study in design and available data. Additional patient factors, such as distance from VA facility, could be important, but were not available. Patient delay was not assessed because it was not consistently recorded in the medical record. More importantly, patient delay is not directly relevant for diagnoses initiated by a positive screening test or by the evaluation of another medical concern. The quality of the data abstraction is not completely known; however, the use of experienced abstractors, centralized training, and standardized protocols give us confidence in the validity of the data. In addition, the quality assessment of the supplemental data abstraction also support the quality of the VA CanCORS data which were abstracted the same research personnel. Finally, we did not have data to investigate other potential adverse outcomes of delayed diagnosis, such as decreased patient satisfaction or increased anxiety.
Patients with symptoms other than GI bleeding had as their initial event the first abnormal test (e.g. CT scan for back pain). While this approach is straightforward for non GI symptoms, it could be argued that a patient with any GI symptom should have had the first documentation of that complaint as the initial event. The justification for our approach is the dearth of convincing evidence that non-bleeding GI symptoms are strongly predictive of cancer or significant neoplasia (e.g. large adenomas). In a study of consecutive colonoscopies 13% of patients with bleeding had cancer or large adenomas (>1 cm) compared to 2% of patients with other GI symptoms which is the expected prevalence in a screening population [6
]. A VA study reported that colonoscopic findings for constipation were similar to findings in an asymptomatic screening population [8
]. Finally, a multicenter study observed the same prevalence of polyps and masses >1 cm during colonoscopies for non-bleeding GI symptoms as for asymptomatic patients undergoing screening [7
]. Rather than mandate specific evaluations to investigate cancer for every GI symptom, efforts should focus on evaluation of bleeding symptoms and, most importantly, performing age-appropriate CRC screening.
Our results do not support current policies for wait time benchmarks such as 60 days from a positive FOBT until colonoscopy or 30 days to see a new consultation. We recognize, however, that policy benchmarks may reflect other considerations such as perceptions of customer service and satisfaction. Future research should directly investigate the impact of wait times on outcomes such as patient satisfaction, anxiety, and adherence to physician recommendations. If a 3 or 4 month wait time does not negatively impact these outcomes compared to a 1 or 2 month wait time then, it may be a better use of resources to improve the screening rates among asymptomatic patients. In this study having a cancer diagnosed via screening was the only factor associated with stage at diagnosis, but only 39% of participants were diagnosed via screening. Although screen-detected patients could have had slower growing disease, screening practice guidelines are based, in part, on prospective randomized trials which also found screening to detect cancer at an earlier stage [19
]. Future research should also address why over half of VA patients were not diagnosed via screening and investigate the process of colorectal cancer diagnosis in other medical systems as well. Our results support that it makes an important clinical difference whether a person is diagnosed when asymptomatic or after symptoms or abnormal tests are noted.