Family History as a Risk Factor for Disease
A positive family history increases risk for common diseases by 2 to 10 times that of the general population. Table 1 displays prevalence and risk for disease based on family history.
Odds ratio (OR) and relative risk (RR) ratios are also given in Table 1 . The odds ratio reflects how much more likely it is that the disease will occur given the family history (eg, twice as likely, 10 times as likely, etc.), compared with the general population. Relative risk, calculated differently, conveys the probability of developing the disease based on family history. For example, the OR for colorectal cancer in someone with 2 affected first-degree relatives is 4.9, meaning that this person has almost 5 times greater odds of developing colorectal cancer than the general population. The probability of someone acquiring type II diabetes is 2.4 times greater if his/her mother had type II diabetes.
Studies indicate that more than 30%, and perhaps as many as 40%, of patients have a significant family history, placing them at risk of developing a chronic disease Family history remains underutilized as a tool to assess risk and guide early detection and prevention strategies.
A recent study of early and late onset coronary heart disease in first- and second-degree relatives identified an increased risk of approximately fivefold for early onset heart disease given a strong familial risk, and a twofold increase given a moderate familial risk. The data identified that diabetes, hypercholesterolemia, hypertension, and obesity aggregate in high-risk families, and the risk of coronary heart disease associated with moderate and strong risk increases when these conditions are present and decreases when they are absent. This emphasizes the importance of stratifying risk based on family history and intervening where possible.
Because a complete and thorough family history seems to be more the exception than the rule, it is important to explore barriers that impede clinicians' ability to elicit this information in a thorough and precise manner. More than a knowledge deficit on the part of clinicians, other barriers also affect the clinician's ability to interpret family histories and counsel patients regarding risk. Suther and Goodson identified additional constraints such as time limitations, lack of referral guidelines, a dearth of genetics professionals, and reimbursement issues.
Pedigree analysis (a multigenerational graphic recording of family medical history using symbols to recognize patterns) can take up to 30 minutes, which is often prohibitive during primary care office visits. A study by Acheson found that the average discussion time devoted to obtaining family history in primary care was less than 2.5 minutes. Improved collection tools must be developed to assist healthcare providers to efficiently gather a family history and effectively assess risk.
In 2005, the CDC began evaluating a Web-based tool and algorithm called "Family Healthware." This tool collects information about health behaviors, use of screening tests, and health history for 6 diseases (coronary heart disease, stroke, diabetes, and colorectal, breast, and ovarian cancer). This tool also provides recommendations for lifestyle changes and screening.With current research focused on the development of family history risk assessment instruments, research on the validity and clinical utility of these tools will be ongoing.
Topics in Advanced Practice Nursing eJournal © 2008 Medscape
Cite this: Integrating Genetics Into Primary Care: Family History Is Key - Medscape - Jun 18, 2008.