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Chronic Obstructive Pulmonary Disease (COPD) in Norway
- According to the latest Tromsø Study, about 6 per cent of the population over 40 years old has COPD. This corresponds to 150,000 people in the country as a whole.
- Most COPD patients display mild symptoms and many are unaware that they have the disease.
- Chronic diseases in the lower respiratory tract (which include COPD) were the third most frequently reported cause of death in 2016.
- The number of people living with COPD will remain high in the coming years because the number of older people is increasing.
- Smoking is the main cause of COPD.
Chronic Obstructive Pulmonary Disease (COPD) can cause significant disability. The first signs of COPD are chronic cough and sputum in the morning as well as breathlessness after physical exertion. In serious cases, breathing problems may also occur at rest.
Many people contact the health service with acute deterioration of symptoms (exacerbations) that are triggered by infections.
The following data are used:
- Health registries: Cause of Death Registry, Norwegian Patient Registry (NPR), Register for Control and Payment of Health Reimbursements (KUHR) at the Norwegian Directorate of Health, Norwegian Prescription Database.
- Population studies including the Hordaland Study, Health Studies in Nord-Trøndelag (HUNT) and the Tromsø Studies.
Number treated by the health service
Approximately 55,000 people were treated for COPD in 2016. Figure 1 shows the number of patients treated for COPD in the health service during the period 2008-2014 (Skogen, 2017). There has been an increase and most were treated in primary care.
Figure 1. The number of people diagnosed with COPD in primary and specialist health services. The figure shows the number of patients treated only in primary care (KUHR, diagnostic codes (ICPC-2 code R95), only in specialist health service (NPR, ICD-10 J43 or J44 diagnosis box) or in both primary and specialist healthcare services (KUHR + NPR). Figures for the period 2008 to 2014. Source: KUHR and NPR.
If adjustments are made for changes in the age composition of the population, we see that the proportion treated for COPD has been very stable throughout the period 2008-2014, see Figure 2.
Figure 2. Proportion of women and men in the population who consulted both primary and specialist health services for COPD in the period 2008-2014. Data source: NPR, KUHR.
Over 84,000 people received drug treatment for COPD in 2014 (Norwegian Prescription Database).
Hospital admissions: Approximately 11,000 patients were admitted to hospital for acute COPD deterioration in 2015. On average, they were admitted 1.6 times during that year. On average, 29.3 per cent of all primary admissions were followed by readmission within 30 days. This is shown by figures from the Centre for Clinical Documentation and Evaluation (SKDE, 2017). The acute admissions are those with the most severe symptoms.
COPD in the population
COPD prevalence is uncertain. Different diagnostic criteria for the COPD diagnosis give different numbers in population studies. In addition, the age composition among the participants in the study and their willingness to participate will affect the prevalence figures.
COPD incidence and diagnostic criteria
When making a diagnosis, symptoms and lung function (spirometry) are taken into account. The lung function is stated as FEV1 / FVC values.
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommends 0.70 as the age-independent limit value for FEV1 / FVC. However, this contributes to over-diagnosis among the elderly and under-diagnosis among the middle-aged. Many medical environments therefore recommend using "lower limit of normal" (LLN) from GLI-2012 which takes into account how age affects FEV1 / FVC. If LLN is used, we see a small increase in COPD with age and thus less over-diagnosis among older age groups (Langhammer, 2016; Quanjer, 2012).
Earlier population studies reported that 7-10 per cent of the population aged over 40 years had a lung function consistent with COPD, if the GOLD criteria are taken into account (Johannessen, 2005). GOLD uses the following as a basis for a COPD diagnosis: the patient has a FEV1 / FVC measurement below 0.7 after using bronchodilatory medication and also has a cough or breathlessness.
The Tromsø Study from 2015-16 gives the following figures for COPD prevalence (Hasse Melbye, personal communication):
- COPD incidence based on the GOLD criteria: Among participants who were 40 years or older, 20 per cent had reduced lung capacity (FEV1 / FVC <0.7), but only 11 per cent reported breathlessness or coughing. According to the GOLD criteria, both must be present before making a COPD diagnosis. Therefore, 11 per cent would receive a COPD diagnosis according to the GOLD criteria. If the participant had taken bronchodilatory medication before the lung function measurement (as the GOLD criteria also assumes), the proportion would be somewhat lower than 11 per cent.
- COPD incidence based on the LLN criteria: Among the participants aged 40 and over, 6 per cent of people in Tromsø had COPD. Of these, 32 per cent had been diagnosed with COPD and 50 per cent had either COPD or asthma before they were examined in connection with the Tromsø Study. Many with COPD or a combination of asthma and COPD had "asthma" as a diagnosis, so they were probably unaware that they had COPD.
On a national basis, the results from the last Tromsø Study indicate that about 150,000 people aged over 40 years have COPD, and that between 50,000 and 75,000 of these are treated for COPD in the health service. This corresponds with the data we have from the Norwegian Patient Register, KUHR and the Norwegian Prescription Database.
Prevalence increases with age
Increasing life expectancy, including among those with COPD, will contribute to the number of people living with COPD remaining high in the years to come. However, the reduction in the number of smokers will reduce the number of new COPD cases and counteract the increase.
Few population studies show the COPD prevalence over time. An exception is a study from northern Sweden that followed COPD prevalence from 1994 to 2009 (Backman, 2016).
Several diagnostic criteria were used and a tendency to reduced incidence was found when adjustments were made for age composition. For example, age-adjusted incidence in the Swedish population would have fallen from 10.5 per cent in 1994 to 8.5 per cent in 2009 if the GOLD criteria were followed. The downward trend was even clearer when other criteria were used. Similar findings have been made in Spain (Soriano, 2010).
The Health Study in Nord Trøndelag in 1995-1997 showed that more men than women had COPD (Leivseth, 2013). However, the gender differences in COPD are becoming smaller. Different smoking habits over time are one of the reasons for this (see below).
People with a primary education have a three times higher risk of COPD than people with a higher education. This is still the case when differences in smoking habits and occupation are accounted for (Bakke, 1995). The underlying causes are unknown but conditions throughout the course of life that vary with socioeconomic status may affect the development of COPD.
Chronic diseases in the lower respiratory tract (including COPD) were the third most frequently reported cause of death in Norway in 2015, after cardiovascular disease and cancer (NIPH; Cause of Death Registry). This corresponds with figures from other Western countries; see the section on international prevalence below.
Figure 3 shows that there was a slight increase in the number of deaths due to chronic diseases of the lower respiratory tract in the period 2006-2015. There is little difference between the sexes. These statistics include deaths from chronic lower respiratory diseases in total, but COPD constitutes the largest group among these.
Figure 3. The number of deaths from chronic diseases in the lower respiratory tract (COPD, emphysema, asthma, chronic bronchitis (J40-J47)) for women and men in the period 2006-2016. Source: Cause of Death Registry.
The number of deaths is similar for women and men but age-adjusted mortality rates (deaths per 100,000 inhabitants) are still highest among men (see Figure 4).
Age-adjusted mortality from COPD has decreased somewhat among men since 2008, but appears to be stable among women.
Figure 4. The number of deaths per 100,000 inhabitants from chronic diseases in the lower respiratory tract (COPD, emphysema, asthma, / chronic bronchitis (J40-J47)), women and men in the period 2006-2016. Age-adjusted figures (Eurostat standardised rate). Source: Cause of Death Registry, Norwegian Institute of Public Health.
A study from the Nordic countries (including Norway) shows that one in five people admitted to hospital with acute COPD exacerbation will die within the first two years after admission (Hallin, 2007).
COPD in other countries
Reports from countries in Europe and North America indicate a similar occurrence and change in occurrence as seen in Norway (Buist, 2007; Mannino, 2007).
Risk factors and prevention
Smoking is the main cause of COPD and can explain two out of three cases. The risk increases with increasing tobacco consumption, both when we measure consumption by number of cigarettes per day and smoking over time (smoking years). Smokers have slightly more than a four times higher risk of developing COPD than non-smokers (Johannessen et al., 2005).
Women started smoking later than men. Figure 5 shows the proportion of daily smokers among women and men in the period 1927-2016. The proportion of smokers among women was significantly lower than among men until the late 1960s, whereas in recent years there have been no major differences between the sexes.
Figure 5. Percentage of daily smokers among women and men aged 16-74 years in Norway in the period 1927-2016. Source: Statistics Norway / Norhealth.
The development of chronic respiratory diseases has shifted with changes in smoking habits. Many women who have smoked for many years have now reached an age with an increased risk of COPD. Although there has been a decline in the proportion of smokers among both men and women over recent years, damage from earlier smoking can explain much of the increase in the prevalence and deaths from COPD in women. Prior to that, patients with COPD quit smoking to a much smaller degree than those with heart disease. Now, they quit at similar rates (Danielsen, 2016).
Quitting smoking is therefore the most important preventative measure for COPD.
Influenza can exacerbate COPD, so COPD patients should take the influenza vaccine (NIPH, 2016).
Other risk factors
Working environment: People who work in environments with quartz dust and metal-containing gases, or in mines and tunnels, are at increased risk of COPD.
Outdoor air pollution can exacerbate COPD.
Internal climate: In countries where wood or other biomass is used for domestic heating and cooking, and where ventilation is poor, have high levels of indoor air pollution. This is a significant cause of COPD in some countries.
Passive smoking: There is a lack of knowledge about the link between passive smoking and COPD development.
Premature birth can cause lung damage that increases the risk of COPD in later life. It is uncertain whether the maximum lung function or COPD-related lung loss in adulthood that contributes to this.
Family history / genetics
The increased risk of developing COPD may also be due to hereditary factors, such as low levels of the alpha-1 antitrypsin protein that is important for good lung function.
COPD patients are at increased risk of multiple diseases (comorbidity)
- COPD patients are at increased risk of comorbidity (Rabe, 2013). It is unclear whether this is because COPD contributes to general inflammation in the body or if there are common risk factors for COPD and other diseases. This applies to cardiovascular disease, osteoporosis and possibly depression.
- A high risk for lung cancer and heart failure is associated with pulmonary changes.
- Pressure in the blood vessels of the lungs increases the risk of heart failure.
- Inactivity, deficient diet and little sun exposure due to COPD may increase the risk of osteoporosis, depression and obesity.
- Many patients with COPD and / or asthma receive high cortisone doses. This can contribute to osteoporosis, diabetes, and thin and fragile skin with increased bleeding.
Treatment can relieve symptoms and limit deterioration, but if COPD is present, treatment cannot repair any lost lung function. However, stopping smoking can inhibit deterioration of the disease and further loss of lung function (Eagan, 2004).
Drugs and various interventions can alleviate the symptoms. The interventions work best if the disease is diagnosed early in its progress. The most important argument for early diagnosis is that it can help patients to stop smoking (Danielsen et al., 2016).
Physical activity can help the patient to achieve more activity with low lung function. Activity is beneficial for both functional level and quality of life.
- Gain a better overview of the prevalence and severity of COPD in the Norwegian population and how this is reflected in the use of primary and specialist health services.
- Learn more about how gender, social inequality and lifestyle affect incidence and severity.
- Evaluate diagnostic criteria and the quality of COPD data in Norwegian health registries.
- Learn more about comorbidity and the course of COPD.
- Promote smoking cessation in general and especially among people with COPD.