Symptoms of RTI in the previous week were reported by 12.4%. Somewhat higher frequencies have been found in previous studies [1, 2, 6]. The relatively low frequency of reported RTI symptoms may be explained by a low occurrence of influenza in Norway during the study period (2007–2008) . The mild influenza outbreak may also explain the moderate fluctuation in the frequency of RTI symptoms throughout the year. We found reduced frequency in the elderly, as did van Duijn and coworkers . The participants who were 75 years of age or older attributed most strongly to the reduced frequency in our study, and a poorer recall among the eldest patients, may possibly explain some of the age effect. Current smoking and GOLD 2–4 spirometry were also strongly associated with the reporting of RTI symptoms. The main reason for this was possibly the longer duration of symptoms in subjects who smoked or had obstructive disease and not an increased incidence of new symptoms, since RTI symptoms that had started in the previous week were not over-represented in these subgroups. Increased reporting of RTI symptoms has previously been found in patients with severe COPD , but such patients represented too small a percentage of the subjects with self-reported asthma/COPD or undiagnosed bronchial obstruction, to have had an impact on the results.
Among the 1424 subjects with FEV1/FVC <0.7, only 380 (26.7%) reported to have asthma or COPD. This cannot be explained by incorrect reporting of diseases, since only 4% of those who reported taking respiratory medicine the examination day belonged to the undiagnosed subgroup with bronchial obstruction. Similar frequencies of undiagnosed bronchial obstruction has been found in previous population based studies [18–20]. This study adds that subjects with undiagnosed bronchial obstruction with pre-bronchodilator FEV1/FVC <0.7 and FEV1 <80% predicted, experience prolonged RTI symptoms, similar to subjects with an established diagnosis of asthma or COPD.
Only 5.1% with RTI symptoms had visited a doctor. This is a considerably lower frequency than reported in previous studies [4–6] and may mirror the trend of decreased consultation rates for RTI found in other countries, such as Sweden and the UK [3, 8]. The low frequency of influenza in the study period  may also have contributed to the low consultation rate. The influenza virus tends to give more severe symptoms than other respiratory viruses , with a high consultation rate as a result [5, 7]. We found particularly low care-seeking in the winter season. May be people find it more acceptable to have RTI in winter than during other seasons?
The consultation rate among those with undiagnosed bronchial obstruction was remarkably low, just 2.4%. The members of this subgroup had, to a lesser degree, given up smoking and seldom reported bad health, compared to those with bronchial obstruction who reported asthma or COPD. They may have had an increased tendency to postpone health care. Health contacts are not merely a result of individual symptom recognition. Bodily sensations become symptoms only when interpreted as such by the patient Potentially alarming symptoms are sometimes contained in specific social situations  and related to cultural values and explanations , regarding what is illness and what is poor health . A low consultation rate combined with good self-rated health, despite (although undiagnosed) bronchial obstruction and increased duration of RTI symptoms, points to contextual determinants of symptom interpretation and care-seeking. Reluctance to be confronted with advice to stop smoking may, for instance, have led to a decreased preference of visiting a doctor .
Detecting COPD among patients with RTI in primary care, has been suggested as a strategy for case-finding . The low frequency of consulting a doctor among those with undiagnosed bronchial obstruction in the present study, supports that a more comprehensive approach should be applied for early diagnosis of COPD .
The prescribing rate when a doctor was consulted (41%) was as expected in Nordic countries [8, 28]. The majority of those who had taken antibiotics, did not report to have visited a doctor. A quarter of these belonged to the subgroup with self-reported asthma or COPD, who probably had antibiotics for self-administration at home. Some might have contacted a doctor by phone and received a prescription that way, whilst others may have taken residual tablets from previous prescriptions. Self-medication with antibiotics occurs to a varying extent throughout Europe . In the northern and western parts it is almost impossible to buy antibiotics directly from the pharmacy, and self-medication from left-overs is the most likely way self-medication occurs [29, 30]. It is likely that this had happened in our study population as well.
Reducing the prescription of antibiotics is a major target in combating the emerging resistance among human pathogens . Still, it is important that those who actually need antibiotics get their medication without delay. RTIs are the main cause of exacerbations among patients with COPD  and often requires treatment with antibiotics . It is well known that patients with COPD often are given prescriptions for short courses of oral steroids and antibiotics for self-administration during acute exacerbations, but the benefit of such practice is questionable .
Strengths and limitations
Our study had the strength of being a population based survey with a high attendance rate, with information obtained directly from the subjects about their symptoms and what they actually did when symptoms occurred. Some age groups were more strongly represented in the study sample than others. The analyses by age groups indicates that this selection probably had little impact on the main results, and adjustment for age has been done in the logistic regression. It has been shown that participants in the Tromsø study are somewhat healthier than non-participants, and a too low frequency of RTI symptoms may have been found.
Post-bronchodilator spirometry was not carried out, and all subjects with FEV1/FVC <0.7, or even GOLD 2–4 spirometry, do not really have COPD or a combination of asthma and COPD.
Some conditions associated with our study, may have contributed to the low care-seeking rate reported. The participants were invited to an extended medical examination, and some with RTI symptoms might have postponed a visit to their own doctor, relying on their forthcoming medical check-up. This statement is supported by the fact that many of the participants expressed confidence that “everything” had been checked when they attended. We do not have information about symptoms among the non-participants. It is likely that some of these felt too ill to attend and might have contacted their own doctor to a greater extent, than those who felt well enough to participate.