Because of the increasing prevalence rate of lifestyle-related diseases such as cardiovascular diseases and diabetes mellitus [1–3], but also chronic kidney diseases, population-based prevention strategies are needed to prevent future problems for patients and to reduce costs for health care. Therefore, screening for risk factors of these chronic diseases in the general population becomes more popular. In 2006, the Dutch Kidney Foundation started a program to detect persons at risk for chronic renal failure (CRF) in the Netherlands by offering a free self-test for albuminuria . Patients with CRF have structural abnormalities of the kidney resulting in decreased kidney function, necessitating dialysis or kidney transplantation .
With advertisements on the radio, television, newspapers and the Internet, Dutch adults over the age of 18 were invited to order the free albuminuria self-test via the Internet or by telephone in the period September until November 2006. The presence of an increased amount of albumin in the urine is an indicator for worsening kidney function and increases the risk of developing CRF. In case of a positive test result, participants were advised to visit their General Practitioner (GP) for additional examination and treatment . In the Netherlands, the GP has a gatekeeper role for access to specialized care. All Dutch citizens are listed with a general practice and the GP is usually the first professional to be consulted with health problems.
In a previous study the usefulness of the albuminuria self-test program was investigated in a population of participants who ordered the self-test [4, 6]. From that study it was concluded that more than half of the adult Dutch population was aware of the self-test program and over one million persons (about 9% of the Dutch adult population) ordered the self-test via the Internet in the first 30 days of the program. Also GP visits following a positive test result have contributed to newly detected patients with kidney diseases, hypertension and/or diabetes mellitus. Besides these positive findings, there were also some negative side-effects, which are common in screening programs in the general population. A large number of (probably) false positive test results were found. This causes worries among the test users, unnecessary use of health care and therefore unnecessary costs. Also, due to the low a-priori risk on CRF in the general population, it would have been better to test in populations at high risk. Finally, only a small proportion of the persons with a positive test result (25%) visited a GP for additional examination and/or treatment within eight weeks after testing .
Given the high awareness of the self-test program, it is likely that the program not only resulted directly in newly detected diseases, but also indirectly led to an increased number of newly detected kidney diseases, since 1) instead of self-testing, patients could have decided to visit their GP for testing the renal function, and 2) GPs could have become more focused on the detection of kidney diseases as a result of the program. In our previous study questionnaires of participants were used and therefore it was not possible to determine the consequences of the self-test program for the GP.
Therefore, in this study we have investigated the influence of the screening program on the number of GP contacts for urinary complaints and/or kidney diseases and the number of newly diagnosed patients with kidney diseases by the GP. Accordingly, the following research questions were formulated: 1) Are there differences in the total number of GP contacts for urinary complaints and/or kidney diseases before and after the albuminuria self-test program?, 2) Are there differences in the number of newly diagnosed patients with kidney diseases by the GP before and after the albuminuria self-test program?, and 3) Are there differences in the number of newly diagnosed patients in persons with hypertension and/or diabetes mellitus and patients without these risk factors before and after the albuminuria self-test program?