- Email: [email protected]
Continuity of care and early diagnosis of head and neck cancer
Oral Oncology (2006) 42, 510–516
http://intl.elsevierhealth.com/journals/oron/
Continuity of care and early diagnosis of head and neck cancer Britt C. Reid
a,*
, R. Gary Rozier
b,1
a
Department of Health Promotion and Policy, Health Services Research Program, Room 3A-08, School of Dentistry, University of Maryland, Baltimore, 666 West Baltimore Street, Baltimore, MD 21201, United States b Department of Health Policy and Administration, CB#7411 McGavran-Greenberg Bld, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7411, United States Received 30 August 2005; accepted 5 October 2005
KEYWORDS
Summary This study investigated whether receiving continuous regular care with the same primary care provider had an independent association with stage at diagnosis for head and neck cancers (HNCA) in a Medicare population. The study database (N = 10,662) linked files from the Surveillance, Epidemiology, and End Results Program 1991–2000 for patients with cancers of the oral cavity, pharynx, and larynx with their files from the Center for Medicare and Medicaid Services Program. Continuity of care displayed a statistically significant independent association and dose–response pattern with stage at diagnosis when the provider was an internist but not a general or family physician. An independent statistically significant association between continuity of care with an internist and stage at diagnosis was found for oral cavity tumors (adjusted odds ratio [AOR] = 0.85; 95%CI = 0.73– 0.99), but not pharyngeal tumors (AOR = 1.02; 95%CI = 0.74–1.41). Laryngeal tumors were borderline statistically significant at p-value = 0.07 (AOR = 0.84; 95%CI = 0.69– 1.02). Regular continuous care from the same primary care provider displayed an independent association with early diagnosis of HNCA when the anatomic site was the oral cavity and the provider was an internist, but not when the provider was a general or family physician. Primary care physicians including general/family physicians may represent a relevant group for encouraging increased opportunistic HNCA screening efforts among their patients. c 2005 Elsevier Ltd. All rights reserved.
Health services; Head and neck cancer; Screening; Medicare
* Corresponding author. Tel.: +1 410 706 4923; fax: +1 410 706 3028. E-mail addresses: [email protected] (B.C. Reid), gary_ [email protected] (R.G. Rozier). 1 Tel.: +1 919 966 7388; fax: +1 919 966 6961.
Introduction The concept of a ‘‘medical home’’ has recently taken a more prominent place in both research
1368-8375/$ - see front matter c 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.oraloncology.2005.10.009
Continuity of care and early diagnosis of head and neck cancer and policy. Once defined as the simple presence or absence of a usual source of care it has become more complex over time including the current definition from the American Academy of Pediatrics that describes seven different dimensions for a medical home.1 Most definitions of a medical home minimally include the requirements that health care be accessible, continuous, comprehensive, and coordinated. Recent reviews report that having a medical home is associated with numerous positive health outcomes and process measures including patient satisfaction, reduced treatment delays, reduced hospitalizations, fewer missed work days, and lower costs.2–4 However, most of these same positive outcomes have been found to be the result of continuity of care with a primary care provider5,6 suggesting that for many outcomes relevant dimensions of a medical home may be largely captured, though not completely, by measuring continuity of care. The concept of a medical home may have extensions beyond its origins in pediatric health care. For example, continuity of care has been reported to have benefits in terms of recognizing and treating chronic diseases such as diabetes although benefits may be disease specific and are not consistently found.7,8 Because head and neck cancers are a chronic disease amenable to screening, continuity of care may represent a salutary environment for identifying high-risk patients, screening them, and providing appropriate and timely referrals. More than half of the approximately 28,260 new cases of oral cancer diagnosed in the United States in 20049 were diagnosed at an advanced stage10 despite most early cases being readily detectable by clinical examination.11 An opportunistic strategy targeting high-risk individuals which integrates active screening for head and neck cancers into existing health care services has been suggested.12 Such a strategy is supported, in part, by reports that early head and neck symptoms tend to provide inadequate information for an early diagnosis,13 and that considerable prior contact with primary health care providers exists among head and neck cancer patients.12,14 Continuity of care may enhance opportunistic screening efforts for head and neck cancers. A recent study assessed opportunities for an earlier diagnosis of head and neck cancers in a Medicare population. It found a limited association between increasing numbers of physician visits and local stage at diagnosis that was dependent upon anatomic site and comorbidity status.14 These findings suggested potential missed opportunities for an early diagnosis among the many physician contacts patients had in the year prior to their
511
diagnosis with a head and neck cancer, especially among persons with comorbid conditions. However, the study did not investigate the role played by the visit patterns of patients or the providertypes they visited, both potentially relevant issues. The purpose of this study was to investigate whether regular continuous care with the same primary care provider in the year prior to a head and neck cancer (HNCA) diagnosis, had an impact on stage at diagnosis while accounting for other predictors of stage at diagnosis in a Medicare population. We focus on the most prevalent primary care providers for adults; internists and general/ family practitioners.
Methods Data source The longitudinal dataset used for this study contained Medicare claims for persons diagnosed with head and neck cancer, as reported by the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program from 1991 to 2000. These data included 12 SEER population-based cancer registries that covered approximately 14% of the US population. The Medicare data for this analysis were the claims from all inpatient stays (Medicare Part A), as well as bills from physician and hospital outpatient departments (Medicare Part B). The hospital and physician claims included ICD-9-CM diagnoses for each hospitalization or billed service. Persons in SEER were linked with Medicare enrollment data resulting in 94% of all SEER cancer cases diagnosed in persons 65 years of age or older being found in the Medicare enrollment files. In addition to information about individuals, the SEER-Medicare data were matched by census track and zip code to data from the US Census. These census data were used to obtain the median levels of income and education in the local areas where each patient resided. This study was approved by the Institutional Review Board of the University of Maryland, Baltimore and the Centers for Medicare and Medicaid Services database review committee.
Selection criteria Head and neck cancer cases were comprised of the anatomic sites oral cavity, pharynx, and larynx (ICD-9-CM codes 141.0–148.9, 161.0–161.9). Persons aged less than 65 years at diagnosis, with unknown historic stage, with reason for entitlement
512 as something other than aged 65 years, those with missing demographic data, and those with cancers not microscopically confirmed or that had the reporting source as a death certificate or autopsy were excluded. Also excluded from the analysis were persons not in the Medicare database as of 1991, those without continuous enrollment in Part A and Part B, and those that did not have their first head and neck cancer between 1992 and 2000 as reported in the SEER data. These exclusions ensured that all subjects had at least 1 year of complete data prior to their diagnosis with head and neck cancer so that a pattern of health services usage could be established. The total number of patients in the final analysis cohort was 10,662.
Variable descriptions Stage at diagnosis was classified as localized (historic stages in situ and local) or advanced (historic stages regional and distant). Histologic grade was modeled as a dichotomous variable with the categories grade 1 or unknown, and grade 2 or greater. Histologic grades ‘‘1’’ and ‘‘unknown’’ had similar bivariate relationships with stage at diagnosis and were combined to simplify analysis and presentation. Higher grade scores indicate less histological differentiation. Patient demographic variables race, sex, Hispanic ethnicity, and marital status were modeled as dichotomous indicators. Age was modeled with the categories 65–74 years and 75 years or older. Income and education were ecological variables derived from an algorithm designed to minimize missing data. The algorithm searched for data from the following sources in priority order: year 1990 census tract data, year 2000 census tract data, year 1990 zip code data, and lastly year 2000 zip code data. The 1990 census tract data were available for 97.7% of the study population. Income was assigned based on the median household income of the patient’s census tract/zip code; the resulting continuous variable was then dichotomized into above or at or below the median categories. Similarly, education was determined by the percentage of persons 25 years or older in a patient’s census tract/zip code with 12 or more years of education. The resulting data were then dichotomized into above or at or below the median categories. An alcohol and tobacco-related comorbidity (ATC) variable was derived for this study and described in detail elsewhere.15 The ATC is based on comorbid conditions associated with alcohol and tobacco use and consists of a count of 11 conditions
B.C. Reid, R.G. Rozier present. The approach used to calculate the ATC is similar to the one described in more detail by Klabunde et al.16 The ATC index was collapsed into a dichotomous variable (0, 1 or more) to facilitate presentation of data. A ‘‘continuity of care’’ variable was derived by counting the number of calendar quarters with at least one physician visit to the same provider in the year prior to a diagnosis with head and neck cancer. The resulting ordinal variable had categories of 0, 1, 2, 3 and 4 calendar quarters, with increasing values indicating successively more regular continuous care from the same provider. The categories 3 and 4 were combined for analyses because together they sufficiently capture the concept of continuous care, provide a more stable stratum-specific estimate, and better facilitate display of results. The continuity of care variable was calculated using visits made by a patient to each provider-type. The individual providers, internists and general/family physicians, were determined using their unique provider identification number (UPIN). The ability of this approach to correctly identify whether visits to the same provider occurred was virtually 100%. However, some misclassification of specialty occurred using the UPIN source. The American Medical Association specialty files are suggested as the best source for correctly identifying specialty in Medicare data.17 In this study cohort a cross-tabulation of the AMA and UPIN derived versions of the continuity of care variable displayed agreement of 91.9% for internal medicine and 93.9% for general and family practice.
Statistics The Pearson chi-square test was used to develop p-values where appropriate for comparing proportions. Logistic regression was used to calculate adjusted odds ratios as measures of association with the continuity of care variable modeled as both a dummy (Table 2) and dichotomous variable (Table 3). Odds ratios were determined to be statistically significant when 95% confidence intervals did not include the value 1.00. P-values for linear trend were derived by including continuity of care as an ordinal variable in multiple logistic regression analyses. Analyses were conducted in 2005 using STATA version 8.0 (STATA Corporation, College Station, Texas, 2003 release).
Results Approximately one third of the study population had visits in three or more calendar quarters to
Continuity of care and early diagnosis of head and neck cancer the same primary care provider in the year prior to a HNCA diagnosis. Having continuous care with an internist displayed a statistically significant bivariate association with earlier stage at diagnosis;
Table 1 Percentage of head and neck cancer patients by stage at diagnosis and selected characteristics Local stage Advanced (%) N = 4896 stage (%) N = 5766 Continuity of care with provider-typea,* Internist 20.5 General or family physician 11.8
17.6 11.2
Anatomic site* Oral cavity Pharynx Larynx
45.1 06.4 48.5
46.7 27.0 26.2
Number of ATC conditions* 0 1 or more
32.6 67.4
37.2 62.8
Histologic grade* Grade 1 or unknown Grade 2 or higher
49.2 50.8
25.3 74.7
Age at diagnosis (years) 65–74 75+
53.8 46.2
55.3 44.7
Sex Male Female
66.5 33.5
65.5 34.5
Race* White Non-white
89.3 10.7
86.3 13.7
Ethnicity* Hispanic Non-hispanic
03.2 96.9
04.0 95.9
Marital status* Currently married Not married/unknown
57.9 42.1
49.7 50.3
Incomeb,* Above median At or below median
51.4 48.6
46.7 53.3
Educationc,* Above median At or below median
52.7 47.3
47.2 52.8
ATC, alcohol–tobacco related comorbid condition. a Had visits in three or more calendar quarters to the same physician. b Determined by household income of a patient’s census/ zip code area. c Determined by percentage of adults in a patient’s census/zip code area with 12 or more years of education. * Significant at p-value 6 0.05 (bolded).
513
while having continuous care with a general or family physician did not. Persons with pharyngeal cancer were more likely and persons with laryngeal cancer less likely to have advanced stage tumors. Persons with one or more ATC, higher grade tumors, Hispanic ethnicity, non-white race, or at or below the median for income or education were all more likely to have advanced stage cancer than their respective counterparts (Table 1). Increasingly continuous care from the same provider displayed a statistically significant independent association and dose–response pattern with stage at diagnosis when the provider was an internist, but not when the provider was a general or family physician (Table 2). This estimated association was not changed when visits to non-primary care specialists were added to the model (data not shown). An independent statistically significant association between continuity of care with an internist and stage at diagnosis was found for oral cavity tumors, adjusted odds ratios (AOR) 0.85 (95%CI 0.73–0.99), but not pharyngeal tumors AOR 1.02 (95%CI 0.74–1.41); laryngeal tumors were borderline statistically significant at p-value 0.07 AOR 0.84 (95%CI 0.69–1.02) (Table 3).
Discussion This study found evidence that continuity of care was independently associated with an earlier diagnosis for head and neck cancers, but that this relationship was of moderate strength and dependent on provider-type and anatomic site. A statistically significant dose–response pattern for increasingly more continuous care with an internist and earlier diagnosis was found. However, much of the benefit to patients of an earlier diagnosis was achieved with visits in one or two calendar quarters to the same internist with no apparent additional benefit from visits in three or more quarters. Among the anatomic sites studied, oral cavity tumors had statistically significant associations with earlier diagnosis when the patient received continuous care with an internist, laryngeal tumors had a nearly significant association, and pharyngeal tumors had no such association. Focusing on the anatomic sites most amenable to early diagnosis through screening efforts, it would appear that there may have been missed opportunities for an earlier diagnosis of oral cavity tumors especially among general/family physicians, and missed opportunities for earlier diagnosis of laryngeal tumors irrespective of provider-type. Among the anatomic sites studied,
514 Table 2
B.C. Reid, R.G. Rozier Adjusteda odds ratios for advanced stage at diagnosis and increasingly continuous care by provider-type
Continuity of careb (N = 10,662)
3 or 4 2 1 0
Internist
General/family physician
AOR
95%CI
p-value
AOR
95%CI
p-value
0.80 0.79 0.85 1.00
0.71–0.90 0.69–0.92 0.75–0.96 –
0.01 0.01 0.01 –
0.91 0.97 0.95 1.00
0.80–1.05 0.83–1.15 0.84–1.08 –
0.21 0.75 0.47 –
AOR—adjusted odds ratio, CI—confidence interval. Results significant at p-value 6 0.05 are bolded. a All displayed odds ratios adjusted for age, race, sex, ethnicity, marital status, income, education, comorbidity status, anatomic site and histologic grade. b Number of calendar quarters with at least one visit to the same physician in the year prior to diagnosis with head and neck cancer.
Table 3 Adjusteda odds ratios for advanced stage at diagnosis if patient had continuity of care by provider-type and anatomic site Continuity of careb
Internist GP/FP
Oral cavity N = 4900
Pharynx N = 1874
Larynx N = 3888
AOR
95%CI
AOR
95%CI
AOR
95%CI
0.85 0.94
0.73–0.99 0.78–1.13
1.02 1.09
0.74–1.41 0.72–1.66
0.84 0.92
0.69–1.02 0.74–1.15
AOR—adjusted odds ratio, CI—confidence interval, GP/FP—general or family physician. Results significant at p-value 6 0.05 are bolded. a All displayed odds ratios adjusted for age, race, sex, ethnicity, marital status, income, education, comorbidity status, and histologic grade. b Visits in three or more calendar quarters with same physician in the year prior to diagnosis with head and neck cancer.
oral cavity tumors are often easily detectable clinically while laryngeal tumors often are accompanied by the early symptom of persistent hoarseness.18 These attributes make these anatomic sites highly amenable to opportunistic and symptom-driven screening efforts, respectively. Conversely, pharyngeal tumors are much less amenable to screening and are strongly associated with advanced stage at diagnosis.18 Among patients with pharyngeal cancers, no associations between continuity of care and early stage at diagnosis were found in this study, but it may not be realistic with current screening and detection methodologies to expect dramatic reductions in stage at diagnosis for most tumors at this site. The association between continuity of care and an earlier diagnosis displayed variation by provider-type. The greater potential for missed opportunities for earlier diagnosis of HNCA among family and general physicians than internists may represent levels of provider knowledge and awareness of these cancers in the populations they treat. Several studies of primary care physicians found gaps in oral cancer knowledge, low rates of oral cancer screening, and high interest in obtaining continuing education to enhance their knowl-
edge.19–21 However, these studies did not include internists for comparison. Additionally, the magnitude of the independent association displayed for internists, while statistically significant, was a moderate one, suggesting room for enhanced HNCA screening efforts among internists as well. Alternate explanations for these results could include selection biases, where the characteristics of the patients that choose care from each providertype are affecting the outcome. In an attempt to address this issue many patient characteristics were included in the multivariate models, but residual effects as well as unmeasured characteristics could still have affected the result. Nonetheless, it should be noted that irrespective of the possibility that patient characteristics may play a role in predicting stage at diagnosis, opportunities for an earlier diagnosis of HNCA are going unrealized. Providers with a knowledge of which patient characteristics are associated with stage at diagnosis could increase screening efforts accordingly. Referral patterns may also differ between primary provider-types and help explain differences in stage at diagnosis. However, adjustment by visits to non-primary care specialists in the statistical models did not change the estimated associations.
Continuity of care and early diagnosis of head and neck cancer Another limitation was not having any data on dental visits. Dentists would be expected to diagnose a large number of asymptomatic oral cavity tumors and future studies would be improved by including these data. Conceptually, continuity of care should also promote coordination of care and therefore the expectation to include appropriate referral relationships with dentists for general oral health needs. This may, to an unknown extent, already be reflected in the estimated associations reported here. The use of a Medicare population minimized access to care issues because of their insurance coverage. Few other large subgroups of the US population have similar access to health care. The virtual removal of financial barriers for this subgroup would reduce variation in access to health care and as a result also reduce the magnitude of any associations observed between continuity of care and an earlier diagnosis. Populations without such uniform access to care, including many people younger than 65 years of age may display different relationships. About one-half of all HNCA occurs prior to age 65 years, therefore these study findings may not be representative of patterns present among younger cancer patients. This study exhibited a number of strengths. The sample population has been shown to be generally representative of all US citizens of this age group.22 The relatively large sample size also allowed for stable estimates of effect. A large number of established predictors of stage at diagnosis were accounted for in multivariate models and the longitudinal design and use of unique provider identification numbers allowed for the reliable establishment of continuity of care by providertype. We studied one important characteristic of having a medical home in looking at continuity of care. It is possible that future studies that specifically include more characteristics of a medical home such as access, comprehensiveness, and coordination, may prove even more instructive in revealing predictors of an early head and neck diagnosis. Continuity of care displayed an independent association with early diagnosis of HNCA when the anatomic site was the oral cavity and the provider was an internist, but not when the provider was a general or family physician. Primary care physicians including General/family physicians may represent a relevant group for encouraging increased opportunistic HNCA screening efforts among their patients. The authors have no conflicts of interest concerning this research.
515
References 1. American Academy of Pediatrics. Characteristics of a medical home. Available from: http://aappolicy.aappublications.org/cgi/content/full/pediatrics. Accessed on 06/ 02/2005. 2. Starfield B, Shi LY. The medical home, access to care, and insurance: a review of evidence. Pediatrics 2004;113(5): 1493–8. 3. Strickland B, McPherson M, Weissman G, van Dyck P, Huang P, Newacheck P. Access to the medical home: results of the national survey of children with special health care needs. Pediatrics 2004;113(5):1485–92. 4. Palfrey JS, Sofis LA, Davidson EJ, Liu JH, Freeman L, Ganz ML. The pediatric alliance for coordinated care: evaluation of a medical home model. Pediatrics 2004;113(5):1507–16. 5. Cabana MD, Jee SH. Does continuity of care improve patient outcomes? J Fam Pract 2004;53(12):974–80. 6. Saultz JW, Lochner J. Interpersonal continuity of care and care outcomes: a critical review. Ann Fam Med 2005;3(2): 159–66. 7. Koopman RJ, Mainous III AG, Baker R, Gill JM, Gilbert GE. Continuity of care and recognition of diabetes, hypertension, and hypercholesterolemia. Arch Intern Med 2003;163(11):1357–61. 8. Mainous III AG, Koopman RJ, Gill JM, Baker R, Pearson WS. Relationship between continuity of care and diabetes control: evidence from the Third National Health and Nutrition Examination Survey. Am J Public Health 2004; 94(1):66–70. 9. American Cancer Society. Cancer facts and figures 2004. American Cancer Society, Atlanta, GA, 2004. Available online. Last accessed 25 March 2005. 10. SEER. Surveillance, Epidemiology, and End Results Program 9 registries public-use database (1973–1995). National Cancer Institute August 1997 submission. 4-1-1998. National Cancer Institute, Rockville, MD. 11. Smart CR. Screening for cancer of the aerodigestive tract. Cancer 1993;72(Suppl. 3):1061–5. 12. Prout MN, Heeren TC, Barber CE, Rose L, Morris SG, Hurley C, et al. Use of health services before diagnosis of head and neck cancer among Boston residents. Am J Prev Med 1990; 6(2):77–83. 13. Dolan RW, Vaughan CW, Fuleihan N. Symptoms in early head and neck cancer: an inadequate indicator. Otolaryngol Head Neck Surg 1998;119(5):463–7. 14. Reid BC, Warren JL, Rozier RG. Comorbidity and early diagnosis of head and neck cancer in a Medicare population. Am J Prev Med 2004;27(5):373–8. 15. Reid BC, Alberg AJ, Klassen AC, Rozier RG, Garcia I, Winn DM, et al. A comparison of three comorbidity indexes in a head and neck cancer population. Oral Oncol 2002;38(2): 187–94. 16. Klabunde CN, Warren JL, Legler JM. Assessing comorbidity using claims data: an overview. Med Care 2002; 40(Suppl. 8):IV-35. 17. Baldwin LM, Adamache W, Klabunde CN, Kenward K, Dahlman C, Warren L. Linking physician characteristics and Medicare claims data: issues in data availability, quality, and measurement. Med Care 2002;40(Suppl. 8): IV-95. 18. Vokes EE, Weichselbaum RR, Lippman SM, Hong WK. Head and neck cancer. N Engl J Med 1993;328(3):184–94. 19. Canto MT, Horowitz AM, Child WL. Views of oral cancer prevention and early detection: Maryland physicians. Oral Oncol 2002;38(4):373–7.
516 20. Canto MT, Horowitz AM, Drury TF, Goodman HS. Maryland family physicians’ knowledge, opinions and practices about oral cancer. Oral Oncol 2002;38(5):416–24. 21. Goodman HS, Yellowitz JA, Horowitz AM. Oral cancer prevention. The role of family practitioners. Arch Fam Med 1995;4(7):628–36.
B.C. Reid, R.G. Rozier 22. Warren JL, Klabunde CN, Schrag D, Bach PB, Riley GF. Overview of the SEER-Medicare data: content, research applications, and generalizability to the United States elderly population. Med Care 2002;40(Suppl. 8):IV-18.
http://intl.elsevierhealth.com/journals/oron/
Continuity of care and early diagnosis of head and neck cancer Britt C. Reid
a,*
, R. Gary Rozier
b,1
a
Department of Health Promotion and Policy, Health Services Research Program, Room 3A-08, School of Dentistry, University of Maryland, Baltimore, 666 West Baltimore Street, Baltimore, MD 21201, United States b Department of Health Policy and Administration, CB#7411 McGavran-Greenberg Bld, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7411, United States Received 30 August 2005; accepted 5 October 2005
KEYWORDS
Summary This study investigated whether receiving continuous regular care with the same primary care provider had an independent association with stage at diagnosis for head and neck cancers (HNCA) in a Medicare population. The study database (N = 10,662) linked files from the Surveillance, Epidemiology, and End Results Program 1991–2000 for patients with cancers of the oral cavity, pharynx, and larynx with their files from the Center for Medicare and Medicaid Services Program. Continuity of care displayed a statistically significant independent association and dose–response pattern with stage at diagnosis when the provider was an internist but not a general or family physician. An independent statistically significant association between continuity of care with an internist and stage at diagnosis was found for oral cavity tumors (adjusted odds ratio [AOR] = 0.85; 95%CI = 0.73– 0.99), but not pharyngeal tumors (AOR = 1.02; 95%CI = 0.74–1.41). Laryngeal tumors were borderline statistically significant at p-value = 0.07 (AOR = 0.84; 95%CI = 0.69– 1.02). Regular continuous care from the same primary care provider displayed an independent association with early diagnosis of HNCA when the anatomic site was the oral cavity and the provider was an internist, but not when the provider was a general or family physician. Primary care physicians including general/family physicians may represent a relevant group for encouraging increased opportunistic HNCA screening efforts among their patients. c 2005 Elsevier Ltd. All rights reserved.
Health services; Head and neck cancer; Screening; Medicare
* Corresponding author. Tel.: +1 410 706 4923; fax: +1 410 706 3028. E-mail addresses: [email protected] (B.C. Reid), gary_ [email protected] (R.G. Rozier). 1 Tel.: +1 919 966 7388; fax: +1 919 966 6961.
Introduction The concept of a ‘‘medical home’’ has recently taken a more prominent place in both research
1368-8375/$ - see front matter c 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.oraloncology.2005.10.009
Continuity of care and early diagnosis of head and neck cancer and policy. Once defined as the simple presence or absence of a usual source of care it has become more complex over time including the current definition from the American Academy of Pediatrics that describes seven different dimensions for a medical home.1 Most definitions of a medical home minimally include the requirements that health care be accessible, continuous, comprehensive, and coordinated. Recent reviews report that having a medical home is associated with numerous positive health outcomes and process measures including patient satisfaction, reduced treatment delays, reduced hospitalizations, fewer missed work days, and lower costs.2–4 However, most of these same positive outcomes have been found to be the result of continuity of care with a primary care provider5,6 suggesting that for many outcomes relevant dimensions of a medical home may be largely captured, though not completely, by measuring continuity of care. The concept of a medical home may have extensions beyond its origins in pediatric health care. For example, continuity of care has been reported to have benefits in terms of recognizing and treating chronic diseases such as diabetes although benefits may be disease specific and are not consistently found.7,8 Because head and neck cancers are a chronic disease amenable to screening, continuity of care may represent a salutary environment for identifying high-risk patients, screening them, and providing appropriate and timely referrals. More than half of the approximately 28,260 new cases of oral cancer diagnosed in the United States in 20049 were diagnosed at an advanced stage10 despite most early cases being readily detectable by clinical examination.11 An opportunistic strategy targeting high-risk individuals which integrates active screening for head and neck cancers into existing health care services has been suggested.12 Such a strategy is supported, in part, by reports that early head and neck symptoms tend to provide inadequate information for an early diagnosis,13 and that considerable prior contact with primary health care providers exists among head and neck cancer patients.12,14 Continuity of care may enhance opportunistic screening efforts for head and neck cancers. A recent study assessed opportunities for an earlier diagnosis of head and neck cancers in a Medicare population. It found a limited association between increasing numbers of physician visits and local stage at diagnosis that was dependent upon anatomic site and comorbidity status.14 These findings suggested potential missed opportunities for an early diagnosis among the many physician contacts patients had in the year prior to their
511
diagnosis with a head and neck cancer, especially among persons with comorbid conditions. However, the study did not investigate the role played by the visit patterns of patients or the providertypes they visited, both potentially relevant issues. The purpose of this study was to investigate whether regular continuous care with the same primary care provider in the year prior to a head and neck cancer (HNCA) diagnosis, had an impact on stage at diagnosis while accounting for other predictors of stage at diagnosis in a Medicare population. We focus on the most prevalent primary care providers for adults; internists and general/ family practitioners.
Methods Data source The longitudinal dataset used for this study contained Medicare claims for persons diagnosed with head and neck cancer, as reported by the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program from 1991 to 2000. These data included 12 SEER population-based cancer registries that covered approximately 14% of the US population. The Medicare data for this analysis were the claims from all inpatient stays (Medicare Part A), as well as bills from physician and hospital outpatient departments (Medicare Part B). The hospital and physician claims included ICD-9-CM diagnoses for each hospitalization or billed service. Persons in SEER were linked with Medicare enrollment data resulting in 94% of all SEER cancer cases diagnosed in persons 65 years of age or older being found in the Medicare enrollment files. In addition to information about individuals, the SEER-Medicare data were matched by census track and zip code to data from the US Census. These census data were used to obtain the median levels of income and education in the local areas where each patient resided. This study was approved by the Institutional Review Board of the University of Maryland, Baltimore and the Centers for Medicare and Medicaid Services database review committee.
Selection criteria Head and neck cancer cases were comprised of the anatomic sites oral cavity, pharynx, and larynx (ICD-9-CM codes 141.0–148.9, 161.0–161.9). Persons aged less than 65 years at diagnosis, with unknown historic stage, with reason for entitlement
512 as something other than aged 65 years, those with missing demographic data, and those with cancers not microscopically confirmed or that had the reporting source as a death certificate or autopsy were excluded. Also excluded from the analysis were persons not in the Medicare database as of 1991, those without continuous enrollment in Part A and Part B, and those that did not have their first head and neck cancer between 1992 and 2000 as reported in the SEER data. These exclusions ensured that all subjects had at least 1 year of complete data prior to their diagnosis with head and neck cancer so that a pattern of health services usage could be established. The total number of patients in the final analysis cohort was 10,662.
Variable descriptions Stage at diagnosis was classified as localized (historic stages in situ and local) or advanced (historic stages regional and distant). Histologic grade was modeled as a dichotomous variable with the categories grade 1 or unknown, and grade 2 or greater. Histologic grades ‘‘1’’ and ‘‘unknown’’ had similar bivariate relationships with stage at diagnosis and were combined to simplify analysis and presentation. Higher grade scores indicate less histological differentiation. Patient demographic variables race, sex, Hispanic ethnicity, and marital status were modeled as dichotomous indicators. Age was modeled with the categories 65–74 years and 75 years or older. Income and education were ecological variables derived from an algorithm designed to minimize missing data. The algorithm searched for data from the following sources in priority order: year 1990 census tract data, year 2000 census tract data, year 1990 zip code data, and lastly year 2000 zip code data. The 1990 census tract data were available for 97.7% of the study population. Income was assigned based on the median household income of the patient’s census tract/zip code; the resulting continuous variable was then dichotomized into above or at or below the median categories. Similarly, education was determined by the percentage of persons 25 years or older in a patient’s census tract/zip code with 12 or more years of education. The resulting data were then dichotomized into above or at or below the median categories. An alcohol and tobacco-related comorbidity (ATC) variable was derived for this study and described in detail elsewhere.15 The ATC is based on comorbid conditions associated with alcohol and tobacco use and consists of a count of 11 conditions
B.C. Reid, R.G. Rozier present. The approach used to calculate the ATC is similar to the one described in more detail by Klabunde et al.16 The ATC index was collapsed into a dichotomous variable (0, 1 or more) to facilitate presentation of data. A ‘‘continuity of care’’ variable was derived by counting the number of calendar quarters with at least one physician visit to the same provider in the year prior to a diagnosis with head and neck cancer. The resulting ordinal variable had categories of 0, 1, 2, 3 and 4 calendar quarters, with increasing values indicating successively more regular continuous care from the same provider. The categories 3 and 4 were combined for analyses because together they sufficiently capture the concept of continuous care, provide a more stable stratum-specific estimate, and better facilitate display of results. The continuity of care variable was calculated using visits made by a patient to each provider-type. The individual providers, internists and general/family physicians, were determined using their unique provider identification number (UPIN). The ability of this approach to correctly identify whether visits to the same provider occurred was virtually 100%. However, some misclassification of specialty occurred using the UPIN source. The American Medical Association specialty files are suggested as the best source for correctly identifying specialty in Medicare data.17 In this study cohort a cross-tabulation of the AMA and UPIN derived versions of the continuity of care variable displayed agreement of 91.9% for internal medicine and 93.9% for general and family practice.
Statistics The Pearson chi-square test was used to develop p-values where appropriate for comparing proportions. Logistic regression was used to calculate adjusted odds ratios as measures of association with the continuity of care variable modeled as both a dummy (Table 2) and dichotomous variable (Table 3). Odds ratios were determined to be statistically significant when 95% confidence intervals did not include the value 1.00. P-values for linear trend were derived by including continuity of care as an ordinal variable in multiple logistic regression analyses. Analyses were conducted in 2005 using STATA version 8.0 (STATA Corporation, College Station, Texas, 2003 release).
Results Approximately one third of the study population had visits in three or more calendar quarters to
Continuity of care and early diagnosis of head and neck cancer the same primary care provider in the year prior to a HNCA diagnosis. Having continuous care with an internist displayed a statistically significant bivariate association with earlier stage at diagnosis;
Table 1 Percentage of head and neck cancer patients by stage at diagnosis and selected characteristics Local stage Advanced (%) N = 4896 stage (%) N = 5766 Continuity of care with provider-typea,* Internist 20.5 General or family physician 11.8
17.6 11.2
Anatomic site* Oral cavity Pharynx Larynx
45.1 06.4 48.5
46.7 27.0 26.2
Number of ATC conditions* 0 1 or more
32.6 67.4
37.2 62.8
Histologic grade* Grade 1 or unknown Grade 2 or higher
49.2 50.8
25.3 74.7
Age at diagnosis (years) 65–74 75+
53.8 46.2
55.3 44.7
Sex Male Female
66.5 33.5
65.5 34.5
Race* White Non-white
89.3 10.7
86.3 13.7
Ethnicity* Hispanic Non-hispanic
03.2 96.9
04.0 95.9
Marital status* Currently married Not married/unknown
57.9 42.1
49.7 50.3
Incomeb,* Above median At or below median
51.4 48.6
46.7 53.3
Educationc,* Above median At or below median
52.7 47.3
47.2 52.8
ATC, alcohol–tobacco related comorbid condition. a Had visits in three or more calendar quarters to the same physician. b Determined by household income of a patient’s census/ zip code area. c Determined by percentage of adults in a patient’s census/zip code area with 12 or more years of education. * Significant at p-value 6 0.05 (bolded).
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while having continuous care with a general or family physician did not. Persons with pharyngeal cancer were more likely and persons with laryngeal cancer less likely to have advanced stage tumors. Persons with one or more ATC, higher grade tumors, Hispanic ethnicity, non-white race, or at or below the median for income or education were all more likely to have advanced stage cancer than their respective counterparts (Table 1). Increasingly continuous care from the same provider displayed a statistically significant independent association and dose–response pattern with stage at diagnosis when the provider was an internist, but not when the provider was a general or family physician (Table 2). This estimated association was not changed when visits to non-primary care specialists were added to the model (data not shown). An independent statistically significant association between continuity of care with an internist and stage at diagnosis was found for oral cavity tumors, adjusted odds ratios (AOR) 0.85 (95%CI 0.73–0.99), but not pharyngeal tumors AOR 1.02 (95%CI 0.74–1.41); laryngeal tumors were borderline statistically significant at p-value 0.07 AOR 0.84 (95%CI 0.69–1.02) (Table 3).
Discussion This study found evidence that continuity of care was independently associated with an earlier diagnosis for head and neck cancers, but that this relationship was of moderate strength and dependent on provider-type and anatomic site. A statistically significant dose–response pattern for increasingly more continuous care with an internist and earlier diagnosis was found. However, much of the benefit to patients of an earlier diagnosis was achieved with visits in one or two calendar quarters to the same internist with no apparent additional benefit from visits in three or more quarters. Among the anatomic sites studied, oral cavity tumors had statistically significant associations with earlier diagnosis when the patient received continuous care with an internist, laryngeal tumors had a nearly significant association, and pharyngeal tumors had no such association. Focusing on the anatomic sites most amenable to early diagnosis through screening efforts, it would appear that there may have been missed opportunities for an earlier diagnosis of oral cavity tumors especially among general/family physicians, and missed opportunities for earlier diagnosis of laryngeal tumors irrespective of provider-type. Among the anatomic sites studied,
514 Table 2
B.C. Reid, R.G. Rozier Adjusteda odds ratios for advanced stage at diagnosis and increasingly continuous care by provider-type
Continuity of careb (N = 10,662)
3 or 4 2 1 0
Internist
General/family physician
AOR
95%CI
p-value
AOR
95%CI
p-value
0.80 0.79 0.85 1.00
0.71–0.90 0.69–0.92 0.75–0.96 –
0.01 0.01 0.01 –
0.91 0.97 0.95 1.00
0.80–1.05 0.83–1.15 0.84–1.08 –
0.21 0.75 0.47 –
AOR—adjusted odds ratio, CI—confidence interval. Results significant at p-value 6 0.05 are bolded. a All displayed odds ratios adjusted for age, race, sex, ethnicity, marital status, income, education, comorbidity status, anatomic site and histologic grade. b Number of calendar quarters with at least one visit to the same physician in the year prior to diagnosis with head and neck cancer.
Table 3 Adjusteda odds ratios for advanced stage at diagnosis if patient had continuity of care by provider-type and anatomic site Continuity of careb
Internist GP/FP
Oral cavity N = 4900
Pharynx N = 1874
Larynx N = 3888
AOR
95%CI
AOR
95%CI
AOR
95%CI
0.85 0.94
0.73–0.99 0.78–1.13
1.02 1.09
0.74–1.41 0.72–1.66
0.84 0.92
0.69–1.02 0.74–1.15
AOR—adjusted odds ratio, CI—confidence interval, GP/FP—general or family physician. Results significant at p-value 6 0.05 are bolded. a All displayed odds ratios adjusted for age, race, sex, ethnicity, marital status, income, education, comorbidity status, and histologic grade. b Visits in three or more calendar quarters with same physician in the year prior to diagnosis with head and neck cancer.
oral cavity tumors are often easily detectable clinically while laryngeal tumors often are accompanied by the early symptom of persistent hoarseness.18 These attributes make these anatomic sites highly amenable to opportunistic and symptom-driven screening efforts, respectively. Conversely, pharyngeal tumors are much less amenable to screening and are strongly associated with advanced stage at diagnosis.18 Among patients with pharyngeal cancers, no associations between continuity of care and early stage at diagnosis were found in this study, but it may not be realistic with current screening and detection methodologies to expect dramatic reductions in stage at diagnosis for most tumors at this site. The association between continuity of care and an earlier diagnosis displayed variation by provider-type. The greater potential for missed opportunities for earlier diagnosis of HNCA among family and general physicians than internists may represent levels of provider knowledge and awareness of these cancers in the populations they treat. Several studies of primary care physicians found gaps in oral cancer knowledge, low rates of oral cancer screening, and high interest in obtaining continuing education to enhance their knowl-
edge.19–21 However, these studies did not include internists for comparison. Additionally, the magnitude of the independent association displayed for internists, while statistically significant, was a moderate one, suggesting room for enhanced HNCA screening efforts among internists as well. Alternate explanations for these results could include selection biases, where the characteristics of the patients that choose care from each providertype are affecting the outcome. In an attempt to address this issue many patient characteristics were included in the multivariate models, but residual effects as well as unmeasured characteristics could still have affected the result. Nonetheless, it should be noted that irrespective of the possibility that patient characteristics may play a role in predicting stage at diagnosis, opportunities for an earlier diagnosis of HNCA are going unrealized. Providers with a knowledge of which patient characteristics are associated with stage at diagnosis could increase screening efforts accordingly. Referral patterns may also differ between primary provider-types and help explain differences in stage at diagnosis. However, adjustment by visits to non-primary care specialists in the statistical models did not change the estimated associations.
Continuity of care and early diagnosis of head and neck cancer Another limitation was not having any data on dental visits. Dentists would be expected to diagnose a large number of asymptomatic oral cavity tumors and future studies would be improved by including these data. Conceptually, continuity of care should also promote coordination of care and therefore the expectation to include appropriate referral relationships with dentists for general oral health needs. This may, to an unknown extent, already be reflected in the estimated associations reported here. The use of a Medicare population minimized access to care issues because of their insurance coverage. Few other large subgroups of the US population have similar access to health care. The virtual removal of financial barriers for this subgroup would reduce variation in access to health care and as a result also reduce the magnitude of any associations observed between continuity of care and an earlier diagnosis. Populations without such uniform access to care, including many people younger than 65 years of age may display different relationships. About one-half of all HNCA occurs prior to age 65 years, therefore these study findings may not be representative of patterns present among younger cancer patients. This study exhibited a number of strengths. The sample population has been shown to be generally representative of all US citizens of this age group.22 The relatively large sample size also allowed for stable estimates of effect. A large number of established predictors of stage at diagnosis were accounted for in multivariate models and the longitudinal design and use of unique provider identification numbers allowed for the reliable establishment of continuity of care by providertype. We studied one important characteristic of having a medical home in looking at continuity of care. It is possible that future studies that specifically include more characteristics of a medical home such as access, comprehensiveness, and coordination, may prove even more instructive in revealing predictors of an early head and neck diagnosis. Continuity of care displayed an independent association with early diagnosis of HNCA when the anatomic site was the oral cavity and the provider was an internist, but not when the provider was a general or family physician. Primary care physicians including General/family physicians may represent a relevant group for encouraging increased opportunistic HNCA screening efforts among their patients. The authors have no conflicts of interest concerning this research.
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