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Holden DJ, Harris R, Porterfield DS, et al. Enhancing the Use and Quality of Colorectal Cancer Screening. Rockville (MD): Agency for Healthcare Research and Quality (US); 2010 Feb. (Evidence Reports/Technology Assessments, No. 190.)

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Enhancing the Use and Quality of Colorectal Cancer Screening.

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Appendix GAdditional Material for KQ 4

This Appendix provides supplemental information for KQ4. In addition to the outcomes described in Chapter 3, we found data in the included studies on current volume by provider type and geographic variation in current volume and additional available capacity. Because these measures are related to our outcomes of current volume and additional available capacity, we have completed summary tables and text for these and included here as an Appendix. We also found four additional studies that reported on current volume and additional available capacity in individual states (vs. national level-data reported in Chapter 4). Because results from these studies did not change our conclusions from the national data, we have included them also as part this Appendix rather than in the main text.

The following tables and text provide data on three types of studies: current volume by provider type; geographic variation in current volume and additional available capacity; and current volume and additional available capacity in three states.

Current Volume of Procedures, by Provider Type

Study characteristics. Three studies reported on the distribution of provider types for current volume of FS and colonoscopy (Table G-1).1–3 No study reported projected capacities based on hypothetical scenarios of changes in workforce composition. We rated one study good quality3 and two as fair quality.1–2 Two studies surveyed physicians and measured current volume and provider distribution by self-report of the physician or practice;1,3 one study used claims data from two federal insurers (Medicare and TRICARE)2 to analyze provider type for procedures.

Overview of results. Studies varied in terms of methods (self-report of procedures vs. claims analysis) and had slightly different categorizations of providers. Not surprisingly, results were dissimilar in terms of proportion of procedures (flexible sigmoidoscopy [FS] and colonoscopy) conducted by different provider types.

Detailed assessment, FS. A study by the National Cancer Institute (NCI), which surveyed three types of endoscopic providers, found that FSs in 2003 were performed by primary care physicians (65%), gastroenterologists (25%) and surgeons (11%).1 Seeff et al.,3 in a survey of a national sample of endoscopic facilities, found that FSs were conducted by gastroenterologists (44 percent), primary care physicians (25 percent), surgeons (21 percent), and other providers (11 percent).

Detailed assessment, colonoscopy. Across the three studies (which include four different samples, as one study included TRICARE and Medicare data as separate samples), the range of proportions of colonoscopies conducted by gastroenterologists was 66 to 83 percent; the range of proportions of colonoscopies conducted by surgeons was 11 to 33 percent.1–3 In two studies that used survey data,1,3 the proportion of colonoscopies performed by primary care providers was 1 to 2 percent. In the third study,2 the groups were categorized slightly differently; this study found that 10 percent of colonoscopies were performed by internal medicine physicians.

Table G-1. Current volume of procedures, by provider type

Regional Variation in Colorectal Screening Capacity

Study characteristics. Three studies3–5 examined how capacity to deliver CRC endoscopic screening varies across geographic regions (Table G-2). One study was rated good3 and two fair quality.4–5 One study divided the nation into four census regions;3 two studies examined rural and urban differences in CRC endoscopic capacity.4–5

Overview of results. No conclusions can be made from the very few studies available that examine how additional available capacity varies by geographic region.

Detailed assessment: The single study examining national variation in capacity for CRC screening found that additional available capacity for FS and colonoscopy is the lowest in the South.3 In the study taking place in Montana,4 urban hospitals had more resources in terms of facilities to conduct screening but also less additional available capacity. One-third of the population in this state lived in urban areas, where half of the total capacity was located but where only one-quarter of the unused capacity was located. In comparison, 65 percent of the population lived in rural areas, where half of the total capacity exists, but where three-quarters of unused capacity was located. In the study from Arizona,5 the vast majority of endoscopic procedures were performed in urban areas, and were colonoscopies in both regions (91% in urban and 97% in rural areas). Estimates of additional available capacity were higher in rural than in urban areas (53.1% and 35.7% of current volume, respectively).

Table G-2. Regional variation in current volume and additional available capacity for colorectal cancer screening

State-Level Estimates of Ability of Current Volume or Additional Available Capacity of Colonoscopy to Meet Projected Demand, By Different Demand Scenarios

Study characteristics. Four studies examined state-level current volume for colonoscopy;4–7 three of these also reported additional available capacity for colonoscopy (Table G-3).4–5,7 All four studies were rated fair quality and relied on self-report of surveyed providers or endoscopic screening facilities. Each study that conducted modeling of demand4,6–7 used census data with varying types of refinements to estimate projected demand and ability of capacity to meet that demand. One study used projected changes in capacity as part of the calculations;6 two studies4,7 described the ability of current capacity to meet projected increased demand (under different scenarios). The studies reported data from Arizona, Montana, New Hampshire, and New Mexico.

Overview of results. Differing estimates of current volume were described by two studies; 16 or 20 colonoscopies per week per provider in New Mexico,7 a similar number in Arizona, 5 and approximately 40 colonoscopies per month per provider in Montana.4 Three studies found substantial levels of available, unused capacity: 41 percent of current volume in New Mexico7 and 63 percent in Montana4 is available but unused capacity for colonscopy. In Arizona, 36.5% of endoscopic capacity is available but unused.5 Three studies used simple modeling with varying assumptions and presented different scenarios of projected demand. The Montana study estimated that, using all additional available capacity, the unscreened population in Montana could be screened using colonoscopy by 2013.4 The New Hampshire study6 reported that if capacity (measured by current volume) were to rise by 20 percent, with 60 percent of procedures available for screening, and if compliance with CRC screening increased to 70 percent, capacity would almost meet demand. The New Mexico study concluded that the additional available capacity in New Mexico was sufficient to increase the prevalence of screening rates by 15 percent.7

Table G-3. State-level estimates of colonoscopy current volume, additional available capacity, and ability to meet projected demand


Brown ML, Klabunde CN, Mysliwiec P. Current capacity for endoscopic colorectal cancer screening in the United States: data from the National Cancer Institute Survey of Colorectal Cancer Screening Practices. Am J Med. 2003 Aug 1;115(2):129–33. [PubMed: 12893399]
Robertson RH, Burkhardt JH, Powell MP, et al. Trends in colon cancer screening procedures in the US Medicare and Tricare populations: 1999–2001. Prev Med. 2006 Jun;42(6):460–2. [PubMed: 16563479]
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Ballew C, Lloyd BG, Miller SH. Capacity for colorectal cancer screening by colonoscopy, Montana, 2008. Am J Prev Med. 2009 Apr;36(4):329–32. [PubMed: 19285198]
Benuzillo JG, Jacobs ET, Hoffman RM, et al. Rural-urban differences in colorectal cancer screening capacity in Arizona. J Community Health . 2009 Sep 2 [PubMed: 19728054]
Butterly L, Olenec C, Goodrich M, et al. Colonoscopy demand and capacity in New Hampshire. Am J Prev Med. 2007 Jan;32(1):25–31. [PubMed: 17184962]
Hoffman RM, Stone SN, Herman C, et al. New Mexico's capacity for increasing the prevalence of colorectal cancer screening with screening colonoscopies. Prev Chronic Dis. 2005 Jan;2(1):A07. [PMC free article: PMC1323310] [PubMed: 15670460]
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