A medium-sized primary healthcare center in south-west Finland with computerized patient records was chosen for the study. The healthcare center chosen used electronic patient record system for all patient data archiving. For every patient visit an International Classification of Primary Care (ICPC) code was recorded, and information concerning the cause of visit, clinical findings, results of examinations and treatment suggested was documented. Subjects were all aged > 16 years to include all adults visiting primary health care due to respiratory symptoms. The year 1997 was chosen to represent the situation in the country before the introduction of the 1998 national programme and campaign for detecting and treating COPD, and the year 2002 to represent the impact of the programme.
The population living in the area of this healthcare center in 1997 was 44 402, of whom 36 170 were aged > 16 years. The figures for 2002 were 46 063 and 37 444, respectively. In 1997 and 2002, the number of doctor visits for all causes was 85,535 and 89,787, respectively. For every visit a main diagnosis routinely documented by the treating physician to the healthcare center records was available for the study. All the visits due to respiratory symptoms or diseases were included in the study. Visits due to COPD were identified retrospectively with the help of ICPC (International classification of primary care)  and International Statistical Classification of Diseases and Related Health Problem (ICD10) codes recorded. ICPC codes were used almost solely, and ICD10 codes were used only during primary health care in-hospital periods. In-hospital and polyclinical treatment in specialized health care were not included in the study. The doctors responsible for diagnosing and treating patients did not know about the study when they met the patients. Our aim was to discover all new and pre-diagnosed COPD patients visiting primary health care during each study year. We also included codes of other obstructive respiratory diseases and symptoms suggestive of COPD to find those COPD cases remaining undiagnosed. The overall diagnostic efforts done due to suggestive respiratory symptoms by general practitioners were studied. The diagnosis codes included were those of chronic bronchitis, emphysema, COPD, asthma, cough, dyspnea, wheezing, abnormal sputum and bronchiectasis.
Based on medical record data, patients with respiratory symptoms were divided into two groups: COPD patients and "others". The COPD group was of primary interest. All the available data, including those before our study period, were used.
To be included in the COPD group a patient had to have:
- An earlier diagnosis of COPD made in specialized health care (respiratory clinic).' or
- A suitable history and deteriorated spirometric values. FEV1 had to be ≤ 80% of the predicted value and the FEV1/FVC ratio ≤ 80% according to Finnish clinical practice and guidelines [19, 22].
- Asthma excluded with peak expiratory (PEF) flow measurement data (those having repeatedly ≥ 20% of diurnal variation were excluded from the COPD group).
Other cases formed the group of "others" with respiratory symptoms. Some had asthma or other respiratory diseases, but most had only a variety of respiratory symptoms without specific diagnosis, or at least no diagnosis was made according to the data available.
Pack-years of smoking were computed for current and ex-smokers. One pack-year was regarded as equivalent to 20 cigarettes smoked daily for 1 year. The variables studied included sex, age, history of smoking, PEF and spirometric values.
The main outcomes of the study were the frequency of the use of spirometry for the diagnosis of respiratory symptoms suggestive of COPD and the adequate recording of smoking habits of those seeking medical advice due to their respiratory symptoms.
The statistical analysis was carried out using SPSS and SAS software. Categorical variables were tested by chi-squared test, numerical variables by analysis of variance.
The study was approved by the Salo Healthcare Center Ethical Committee and was performed in accordance with the principles of the Declaration of Helsinki.