The Probability of Specific Diagnoses for Patients Presenting with Common Symptoms to Dutch Family Physicians

,

Original Research

The Probability of Specific Diagnoses for Patients Presenting with Common Symptoms to Dutch Family Physicians

J Fam Pract. 2002 January;51(1):31-36

PDF Download

References

1. Sox HC, Jr. Decision making: a comparison of referral practice and primary care. J Fam Pract 1996;42:155-60.

2. Lamberts H, Hofmans-Okkes IM. Episode of care: a core concept in family practice. J Fam Pract 1996;42:161-67.

3. Kerr LW. Fundamental research at primary care level. Lancet 2000;355:1904-06.

4. Stange KC, Jaén CR, Flocke SA, Miller WL, Crabtree BF, Zyzanski SJ. The value of a family physician. J Fam Pract 1998;46:363-68.

5. Ebell MH, Smith MA, Barry HC, Ives K, Carey M. Does this patient have strep throat? JAMA 2000;284:2912-18.

6. Nutting PA, Green LA. Practice-based research networks: reuniting practice and research around the problems most of the people have most of the time. J Fam Pract 1994;38:335-36.

7. Lamberts H. Episode-oriented epidemiology in family practice: the practical use of the International Classification of Primary Care (ICPC) as illustrated in patients with headache. In: Norton PG, Stewart M, Tudiver F, Bass MJ, Dunn EV, eds. Primary care research: traditional and innovative approaches. Newbury Park, Calif: Sage; 1991;20-72.

8. Donaldson MS, Yordy KD, Lohr KN, Vanselow NA, eds. Primary care: America’s health in a new era. Washington, DC: National Academy Press; 1996.

9. Okkes IM, Oskam SK, Lamberts H. Van Klacht naar Diagnose. Episodegegevens uit de huisartspraktijk. [From complaint to diagnosis: episode data from family practice]. With a CD-ROM. Bussum, the Netherlands: Coutinho; 1998.

10. Hornbrook MC, Hurtado RV, Johnson RE. Health care episodes: definition, measurement and use. Med Care Rev 1985;42:163-218.

11. Solon JA, Feeney JJ, Jones SH, Rigg RD, Sheps CG. Delineating episodes of medical care. Am J Public Health 1967;57:401-08.

12. Okkes IM, Groen A, Oskam SK, Lamberts H. Advantages of a long observation period in episode oriented electronic patient records in family practice. Methods Inf Med 2001;40:229-35

13. Lamberts H, Wood M, eds. ICPC. International classification of primary care. Oxford, England: Oxford University Press; 1987.

14. Lamberts H, Hofmans-Okkes IM. The core of computer based patient records in family practice: episodes of care classified with ICPC. Int J Biomed Comp 1996;42:35-41.

15. Klinkman MS, Green LA. Using ICPC in a computer-based primary care information system. Fam Med 1995;27:449-56.

16. Van Boven C, Dijksterhuis PH, Lamberts H. Defensive testing in Dutch family practice. J Fam Pract 1997;44:468-72.

17. Bentzen N ed. An international glossary for general/family practice. Fam Pract 1995;12:341-69.

18. National Center for Health Statistics. A reason for visit classification for ambulatory care. Hyattsville, Md: National Center for Health Statistics, US Public Health Service; 1979

19. Hofmans-Okkes IM. An international study into concept and validity of the “reason for encounter”. In: Lamberts H, Wood M, Hofmans-Okkes IM, eds. The international classification of primary care in the European community. Oxford, England: Oxford University Press; 1993.

20. Gardner MJ, Altman DG, eds Statistics with confidence. London, England: BMJ; 1989 (floppy disk).

21. Stewart M, Belle Brown J, Weston WW, McWhinney IR, McWilliam CL, Freeman TR. Patient-centered medicine: transforming the clinical method. Thousand Oaks, Calif: Sage; 1995.

22. Green LA, Nutting PA. Family physicians as researchers in their own practices. J Am Board Fam Pract 1994;7:261-63.

23. Franks P, Clancy CM, Nutting PA. Defining primary care: empirical analysis of the National Ambulatory Medical Care Survey. Med Care 1997;35:655-68.

24. National Center for Health Statistics. 1995, 1996, 1997 Ambulatory Medical Care Survey: CD-ROM-series 13. Hyattsville, Md: National Center for Heath Statistics; 1997, 1998, 1999.

25. Okkes IM, Polderman GO, Fryer E, Yamada T, Bujak M, Oskam SK, Green LA, Lamberts H. The role of family practice in different health care systems: a comparison of morbidity data from primary care populations in the Netherlands, Japan, Poland and the US. J Fam Pract 2002;51:72-73.

Since 1985, the members of the Transition Project of the University of Amsterdam Department of Family Practice have been contributing to episodeoriented epidemiology in family practice. We have developed a large prospective database that provides reliable probabilities of diagnoses for symptoms or complaints in a patient of a specific age and sex, suitable for the support of family physicians’ decision making.^2,7,9,16 This article describes the database in more detail and presents data for 4 common symptoms.*

Methods

From 1985 to 1995, 54 Dutch FPs in 23 locations routinely coded episode data for all direct (face-to-face) encounters with their listed patients; within the Dutch health care system, all citizens are listed (registered) with an FP. Each participating FP collected data during a period of at least 1 year; the registration period for patients ranged from 1 to 10 years (mean 2.4).^2,9,16 For each encounter, the patient’s reasons for the encounter, the diagnoses, and the interventions ordered by the physician were coded according to the ICPC. Data were entered on a special encounter form with a copy for a central data entry and included 93,297 patient years, with 236,027 episodes of care and 267,897 direct patient encounters.

Since the FPs had a well-defined practice with listed patients, a precise denominator could be established for the calculation of rates. In the Netherlands, patients can, in principle, not seek specialist care without a referral by their FP. Therefore, especially in a longer observation period, an FP will document a close approximation of the distribution of episodes of care in the Dutch population. In 1 year, 73% of listed patients have a direct encounter with their family physician; in a 2-year observation period this is 92%. It is therefore unlikely that a substantial group of listed patients receive specialist care without their FP’s being aware of it.¹²

A diagnosis could be modified during the course of an episode. If that occurred, the modified diagnosis was applied to all episode data in the analysis. New and ongoing episodes of care were included in a registration year if dealt with at least once; in case of a follow-up encounter in a later registration year, the episode was included again as an ongoing episode. As a consequence, an episode of a chronic disease (eg, diabetes, hypertension) coded in 2 or more registration years was included more than once in the annual prevalence.¹⁷ The average yearly practice population served as the denominator.

As is the case in all time-consuming morbidity studies, the participating FPs were selected, highly motivated, and in this respect, not representative of the average Dutch FP. The database was used in numerous studies, however, and its reliability consistently proved to be high: Approximately 2% of all episodes appeared to be missing in the paper record, and another 2% were erroneously included in the database. The complete reference database is available in Dutch on a CD-ROM attached to a family practice textbook. It includes all combinations of an RFE, a diagnosis, and an intervention for 7 standard age groups at the start of episodes and during follow-up, together with data on comorbidity.⁹

Our paper focuses on prior probabilities, expressed as the top 20 final diagnoses for 4 common reasons for encounter presented at the start of an episode of care^18,19: cough, shortness of breath, general weakness/tiredness, and low back pain without radiation. All probabilities are presented for the total population and for 7 standard age groups, as percentages with 95% symmetric confidence intervals.²⁰ Cells with fewer than 10 observations were excluded. Incidences standardized for the 1995 Dutch population were provided.

Results

(Table 1) shows that for the RFE “cough,” the patient’s age had a substantial impact on the probabilities. The diagnosis of acute bronchitis was common overall but especially in the very young and the very old. This table illustrates the relationships between a common symptom and several diseases with a relatively high incidence (the last column). The prior probabilities were well distributed over the standard table: empty cells occur infrequently.

“Shortness of breath/dyspnoea” as an RFE is associated with a very different distribution of diagnoses than found with cough, especially in the very young and the very old (Table 2). Asthma and acute laryngitis typically occur in the young, while chronic obstructive pulmonary disease, ischemic heart disease, and heart failure occur in the old. Hyperventilation had a peak in young adults. In this table, the relation between a less common symptom and several less common diseases is illustrated. In this case, more empty cells are found. Both cough and shortness of breath mainly relate to respiratory and cardiovascular diseases.