Predictive values of GPs' suspicion of serious disease: a population-based follow-up study

Knowledge is sparse on the prevalence of suspicion of cancer and other serious diseases in general practice. Likewise, little is known about the possible implications of this suspicion on future healthcare use and diagnoses. To study the prevalence of GPs' suspicions of cancer or other serious diseases and analyse how this suspicion predicted the patients' healthcare use and diagnoses of serious disease. Prospective population-based cohort study of 4518 patients consulting 404 GPs in a mix of urban, semi-urban and rural practices in Central Denmark Region during 2008-2009. The GPs registered consultations in 1 work day, including information on their suspicion of the presence of cancer or another serious disease. The patients were followed up for use of healthcare services and new diagnoses through the use of national registers. Prevalence of suspicion was 5.7%. Suspicion was associated with an increase in referrals (prevalence ratio [PR] = 2.56, 95% confidence interval [CI] = 2.22 to 2.96), especially for diagnostic imaging (PR = 3.95, 95% CI = 2.80 to 5.57), increased risk of a new diagnosis of cancer or another serious disease within 2 months (hazard ratio [HR] = 2.98, 95% CI = 1.93 to 4.62)--especially for cancer (HR = 7.55, 95% CI = 2.66 to 21.39)--and increased use of general practice (relative risk [RR] = 1.14, 95% CI = 1.06 to 1.24) and hospital visits (RR = 1.90, 95% CI = 1.62 to 2.23). The positive predictive value of a GP suspicion was 9.8% (95% CI = 6.4 to 14.1) for cancer or another serious disease within 2 months. A GP suspicion of serious disease warrants further investigation, and the organisation of the healthcare system should ensure direct access from the primary sector to specialised tests.