Disease burden in Norway in 2016

Mette C. Tollånes, Ann Kristin Knudsen, Stein Emil Vollset, Jonas Minet Kinge, Vegard Skirbekk, Simon Øverland About the authors
Artikkel

If we aim to address the health challenges facing the population, we must have an overview of the population’s health status. In Norway, mandatory reporting to the Cause of Death Registry means that we have a good overview of diseases and injuries that result in death. The registry publishes annually updated cause of death statistics (1). However, we lack a comparable overview of the prevalence of conditions that result mainly in morbidity, so-called non-fatal health loss. Musculoskeletal disorders and mental disorders, for example, topped the list of causes of sickness absence in Norway in 2017 (2). A comprehensive overview of the health status of a population must include figures for non-fatal diseases.

The Global Burden of Diseases, Injuries and Risk Factors Study (GBD) was launched in the 1990s as a collaboration between the World Health Organization (WHO) and the World Bank. The first report, Investing in Health, was published in 1993 (3). Analyses of disease burden were initiated by the World Health Organization in the late 1990s, but since 2007 the GBD project has been led by the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, USA, with long-term funding from the Bill & Melinda Gates Foundation (4). The GBD project now publishes annually updated estimates of the disease burden from 1990 to the present year for 195 countries and territories, for both sexes and all age groups (34 age categories). The aim is to provide the most detailed and up-to-date overview possible of diseases, injuries and risk factors that result in both death and non-fatal health loss, for use by healthcare authorities, healthcare managers, researchers and the general public (5). The results can be used to show changes in the disease burden over time and to compare the burden of different diseases against one another or between different groups, for example, between countries, sexes or age groups. The most recent cycle of the GBD project (2016) was published in The Lancet in autumn 2017 (610). All results from the project are also freely available via online visualisation tools, also in Norwegian (11).

The Centre for Disease Burden was established at the Norwegian Institute of Public Health in 2017 and collaborates closely with the GBD project. Its main responsibilities are to quality assure and help improve the Norwegian disease burden estimates, disseminate knowledge about disease burden analyses in Norway and conduct research. The aim of this article is to describe the disease burden in Norway in 2016, its development over the last ten years and sex differences in the disease burden.

Material and method

In the following we will briefly describe the operational process in the GBD project, from obtaining health data to producing the final disease burden estimates. Further details can be found in reports from the Centre for Disease Burden at the Norwegian Institute of Public Health (12, 13) and in the most recent Lancet publications, in which the methods are summarised in appendices (610). The key disease burden metrics ‘years of life lost’, ‘years lived with disability’ and ‘disability-adjusted life years’ are defined in Box 1.

Box 1 Years of life lost, years lived with disability and disability-adjusted life years as defined in the Global Disease Burden project (4)

Years of Life Lost (YLLs) are the expected number of years of life remaining when a death occurs. Deaths at a younger age are thus assigned greater weight than deaths in old age

Years Lived with Disability (YLDs) associated with a disease are calculated by multiplying the estimated prevalence of the disease by its disability weight

Disability-Adjusted Life Years (DALYs) are the sum of years of life lost (YLLs) and years lived with disability (YLDs). The total number of disability-adjusted life years in a population for one year can be interpreted as the distance between the current health status of the population and a hypothetical, optimal scenario where the entire population remains healthy (without disability) into old age.

The GBD project has its own list of diseases and injuries, which is organised hierarchically into four levels and is based on the World Health Organization’s classification of diseases (International Classification of Diseases, ICD). The upper level of the hierarchy comprises three groups: i) communicable, maternal, neonatal, and nutritional diseases (also called group 1 diseases); ii) non-communicable diseases and iii) injuries. There are 21 categories in level 2, while the final level consists of 333 diseases/injuries and groupings of these. The list changes over time and is under continual review. The GBD project collects published and unpublished worldwide health data from sources including population and health registries, health surveys and scientific publications, and calculates mortality, non-fatal health loss and disease burden attributable to risk factors.

The statistical models of the GBD project are designed to generate disease burden estimates for all diseases, injuries and risk factors, for both sexes, all age groups, 195 countries/territories and all years (1990–the present year). Where good national data are available, the GBD estimates will be based very closely on these. Where good data are lacking, the models will ‘borrow’ from other years, age groups or similar countries, so that a complete set of estimates is always generated. Estimates are thus produced even when data are inadequate or missing; this is because the absence of an estimate would otherwise often be taken as evidence that the condition does not cause disease burden and thus does not constitute a health problem (5). The exact data sources used, including the Norwegian ones, can be found in a searchable online database (14). There is often a high degree of uncertainty associated with the disease burden estimates, and the GBD project therefore operates with 95 % uncertainty intervals (UI) for all estimates. New data sources are included each year and the methods are continually refined. All calculations are therefore repeated for all calendar years at each annual update.

Calculation of years of life lost

Few countries have mandatory reporting of causes of death. The quality of such data therefore varies throughout the world. In Norway, the Cause of Death Registry has data at the individual level back to 1951 (1). It is the ‘underlying cause of death’, i.e. ‘the disease or injury that initiated the chain of events leading directly to death’ (15), that is shown in the statistics. The GBD project has introduced the term ‘garbage code’ (16) to refer to codes that are used in cause of death statistics, but which cannot from a medical perspective be underlying causes of death, for example, ‘sudden death’, ‘cataracts’ or ‘respiratory failure’. In Norway, garbage codes constitute about 15–20 % of all registered causes of death. For each garbage code, the GBD project defines a set of possible correct underlying causes of death and redistributes the garbage codes among these, resulting in differences between official statistics and GBD statistics.

Years of life lost (YLLs) refers to the expected number of years of life remaining when a death occurs. Remaining years of life are retrieved in the GBD project from a reference mortality table based on the lowest observed mortality rates worldwide, and are equal for both sexes. By taking into account the age distribution among those who died from a specific cause, one can calculate the number of years of life lost due to each disease or injury.

Calculation of years lived with disability

To quantify the number of years lived with disability as a result of a disease, one must know how widespread the disease is and how serious it is for those affected. In Norway, we generally have a limited overview of the prevalence of diseases that result mainly in non-fatal health loss, such as mental disorders and musculoskeletal disorders. The Norwegian estimates for the prevalence of these conditions are therefore largely based on data from other Western European countries.

In the GBD project, severity is expressed in terms of disability weights, which are numbers between 0 (completely healthy) and 1 (deceased). Disability weights are calculated from surveys of the general population and are the same for all countries. Participants are given pairwise descriptions of persons with different medical conditions and are asked to decide which of the two is in better health. By studying how an individual medical condition is rated relative to other medical conditions in repeated pairwise comparisons, one can obtain an estimated relative ranking of all conditions with respect to severity. By asking the participants to compare the value of avoiding death to the value of avoiding chronic disease (for example: Which intervention offers the greatest benefit to public health: one that can prevent 5 000 cases of chronic obstructive pulmonary disease, or one that can prevent 1 000 deaths?), the disability weights can be ‘anchored’ between the extremes of 0 and 1 (8, 12, 17, 18).

Years lived with disability (YLDs) associated with a disease are calculated by multiplying the estimated prevalence of the disease by its disability weight.

Summary measure of disease burden

The sum of years of life lost (YLLs) and years lived with disability (YLDs) is referred to as disability-adjusted life years (DALYs), and represents a summary measure of disease burden. Years of life lost, years lived with disability and disability-adjusted life years can be expressed in numbers and age-adjusted rates per 100 000 persons. Demographic changes in the population, such as population growth and ageing, can be taken into account through the use of age-adjusted rates.

Disease burden attributable to risk factors

Disease burden analyses also include calculations of the proportion of the disease burden attributable to potentially modifiable risk factors. The list of risk factors is also arranged hierarchically and is divided into three main categories: environmental/occupational risks, behavioural risks and metabolic risks. The GBD 2016 project performed calculations for a total of 84 risk factors or groups of risk factors.

Results

The absolute disease burden in Norway increased from 1.16 million disability-adjusted life years in 2006 to 1.21 million in 2016, while the disease burden measured in age-adjusted rates per 100 000 persons decreased by 9 % (95 % uncertainty interval 5–14 %). From 2006 to 2016, the proportion of the disease burden due to years lived with disability increased from 48 % to 52 %, and this proportion was higher in women (57 %) than in men (48 %). Non-communicable diseases accounted for 87 % of the disease burden in 2016, while injuries accounted for 9 %, and infectious, maternal, neonatal and nutritional diseases 4 %.

Non-communicable diseases such as cardiovascular disease, cancer, chronic obstructive pulmonary disease and dementia were responsible for many of the deaths and years of life lost in Norway in 2016, in both women and men (Tables 1 and 2). In both sexes, ischaemic heart disease was by far the most common cause of death, followed by Alzheimer’s disease and other dementias. When calculating years of life lost, deaths that occur at a younger age are assigned greater weight than deaths in old age. Suicide, for example, was ranked in ninth place among causes of death in men in 2016, but was the third most important cause of years of life lost. Deaths due to overdose were also a leading cause of years of life lost in men. In women, breast cancer – which often has a relatively young age of onset – ranked more highly as a cause of years of life lost than of number of deaths. In women, ovarian and pancreatic cancer were also among the ten most important causes of years of life lost. For both of these conditions, however, the 95 % uncertainty intervals overlapped with those for suicide, which was estimated to be responsible for some 6 000 years of life lost among women in 2016.

Table 1

Disease burden in Norway 2016. The ten leading causes of death in 2016 and changes over the period 2006–16

Men

Women

Change3 (%)

Change3 (%)

Number of deaths1 (95 % UI)

Percentage2 (%)

Number

Age-adjusted

Number of deaths1 (95 % UI)

Percentage2 (%)

Number

Age-adjusted

1

Ischaemic heart disease

3 840
(3 359–4 310)

18.6

-11.74

-28.54

1

Ischaemic heart disease

3 639
(3 179–4 118)

17.1

-15.14

-26.74

2

Alzheimer’s disease and other dementias

1 578
(1 279–1 947)

7.7

20.64

-2.9

2

Alzheimer’s disease and other dementias

3 199
(2 615–3 830)

15.1

10.2

-2.6

3

Cerebrovascular disease

1 296
(1 092–1 508)

6.3

-6.5

-23.74

3

Cerebrovascular disease

1 651
(1 355–1 961)

7.8

-16.84

-26.04

4

Cancer of the trachea, bronchus and lung

1 255
(1 071–1 456)

6.1

-1.2

-21.44

4

Chronic obstructive pulmonary disease

1 188
(1 014–1 374)

5.6

13.5

-0.2

5

Prostate cancer

1 158
(837–1 362)

5.6

7.3

-12.6

5

Cancer of the trachea, bronchus and lung

967
(817–1 134)

4.5

12.4

-5.8

6

Chronic obstructive pulmonary disease

1 134
(977–1 312)

5.5

6.6

-12.5

6

Lower respiratory infections

918
(724–1 131)

4.3

-3.4

-17.6

7

Colorectal cancer

878
(752–1 019)

4.3

9.2

-11.7

7

Colorectal cancer

843
(716–987)

4.0

-1.0

-12.3

8

Lower respiratory infections

849
(684–1 033)

4.1

9.4

-12.9

8

Breast cancer

727
(619–844)

3.4

-2.3

-15.64

9

Deliberate self-harm (suicide)

431
(342–598)

2.1

5.0

-12.1

9

Other cardiovascular diseases

636
(544–740)

3.0

1.0

-11.4

10

Fall-related injuries

427
(250–520)

2.1

14.8

-7.7

10

Fall-related injuries

483
(237–610)

2.3

7.4

-5.7

All causes

20 616
(18 319–22 875)

100

3.7

-15.94

All causes

21 255
(18 692–24 015)

100

-1.7

-13.74

1Number of deaths with 95 % uncertainty intervals (UI)

2Percentage of total deaths

3Percentage change 2006–2016 in numbers and age-adjusted rates

4Change significant at 5 % level

Table 2

Disease burden in Norway 2016. The ten leading causes of years of life lost in 2016 and changes over the period 2006–16

Men

Women

Change3 (%)

Change 3 (%)

Number YLLs1
(95 % UI)

Percentage2 (%)

Number

Age-adjusted

Number YLLs1
(95 % UI)

Percentage2 (%)

Number

Age-adjusted

1

Ischaemic heart disease

51 285
(44 281–58 126)

15.6

-15.54

-31.34

1

Ischaemic heart disease

29 438
(25 298–33 667)

11.8

-21.74

-30.24

2

Cancer of the trachea, bronchus and lung

22 924
(19 297–26 751)

7.0

-3.9

-24.24

2

Alzheimer’s disease and other forms of dementia

22 460
(18 335–27 118)

9.0

4.2

-3.0

3

Deliberate self-harm (suicide)

17 263
(13 677–23 272)

5.2

1.2

-14.74

3

Cancer of the trachea, bronchus and lung

17 756
(14 981–20 804)

7.1

7.7

-11.1

4

Cerebrovascular disease

15 615
(13 106–18 196)

4.7

-11.2

-27.44

4

Cerebrovascular disease

14 756
(12 266–17 394)

5.9

-21.54

-29.04

5

Chronic obstructive pulmonary disease

14 530
(12 399–16 970)

4.4

5.3

-14.94

5

Breast cancer

14 191
(11 964–16 622)

5.7

-5.0

-18.24

6

Colorectal cancer

14 352
(12 089–16 752)

4.4

7.8

-13.5

6

Chronic obstructive pulmonary disease

13 824
(11 600–16 332)

5.6

9.5

-5.6

7

Alzheimer’s disease and other forms of dementia

14 027
(11 290–17 421)

4.3

16.34

-3.6

7

Colorectal cancer

12 102
(10 174–14 321)

4.9

-1.4

-14.5

8

Prostate cancer

13 830
(9 925–16 502)

4.2

6.5

-14.1

8

Ovarian cancer

7 095
(5 785–8 565)

2.8

1.9

-13.1

9

Mental disorders due to use of illegal substances

11 353
(8 929–13 754)

3.4

1.0

-13.9

9

Lower respiratory infections

6 574
(5 249–7 931)

2.6

-12.0

-22.04

10

Lower respiratory infections

8 022
(6 536–9 688)

2.4

1.4

-17.1

10

Pancreatic cancer

6 272
(5 227–7 447)

2.5

10.4

-4.5

All causes

329 448
(289 028–369 531)

100

-1.1

-19.24

All causes

249 070
(215 047–286 269)

100

-5.6

-17.34

1Number of years of life lost (YLLs) with 95 % uncertainty intervals (UI)

2Percentage of total years of life lost

3Percentage change 2006–16 in number and age-adjusted rates

4Change significant at 5 % level

In general, age-adjusted rates for the leading causes of both death and years of life lost decreased for both sexes over the period 2006–16 (Tables 1 and 2). Ischaemic heart disease and cerebrovascular disease (stroke) showed the largest decreases with respect to both deaths and years of life lost. For men, the number of years of life lost due to lung cancer, chronic obstructive pulmonary disease and suicide also decreased, and for women there was a decrease in deaths and years of life lost due to breast cancer.

Musculoskeletal disorders, especially low back and neck pain, and mental disorders, especially anxiety disorders and depressive disorders (Table 3), were responsible to a large degree for years lived with disability. Diseases of the skin and subcutaneous tissue, sense organ diseases and oral disorders also appeared high on the list for both sexes. Migraine and diabetes mellitus were also key causes of years lived with disability.

Table 3

Disease burden in Norway 2016. The ten leading causes of years lived with disability in 2016 and changes over the period 2006–16

Men

Women

Change3 (%)

Change3 (%)

Number YLDs1
(95 % UI)

Percentage2 (%)

Number

Age-adjusted

Number YLDs1
(95 % UI)

Percentage2 (%)

Number

Age-adjusted

1

Low back and neck pain

45 061
(31 622–60 501)

15.1

12.64

-4.3

1

Low back and neck pain

53 351
(37 570–70 603)

15.9

17.94

4.4

2

Diseases of the skin and subcutaneous tissue

22 153
(15 105–31 527)

7.4

15.14

1.4

2

Diseases of the skin and subcutaneous tissue

27 015
(18 272–38 855)

8.1

12.34

1.5

3

Sense organ diseases

18 655
(12 648–26 725)

6.2

19.74

-1.0

3

Migraine

25 611
(16 595–35 874)

7.7

12.74

0.9

4

Depressive disorders

13 623
(9 391–18 563)

4.6

19.24

3.1

4

Depressive disorders

21 322
(14 715–28 906)

6.4

17.94

5.0

5

Fall-related injuries

13 246
(8 923–18 587)

4.4

18.74

0.7

5

Anxiety disorders

19 682
(13 940–26 696)

5.9

11.44

-0.4

6

Migraine

12 311
(7 885–17 310)

4.1

14.94

0.5

6

Sense organ diseases

18 838
(12 832–26 538)

5.6

10.34

-1.1

7

Diabetes mellitus

11 975
(8 235–16 590)

4.0

17.44

-3.7

7

Fall-related injuries

13 149
(9 261–18 037)

3.9

15.44

4.3

8

Anxiety disorders

11 272
(7 856–15 376)

3.8

14.84

-0.1

8

Oral disorders

12 697
(7 936–18 740)

3.8

16.54

1.9

9

Oral disorders

11 065
(6 717–17 277)

3.7

22.34

1.2

9

Other musculoskeletal disorders

9 684
(6 471–13 465)

2.9

-9.3

-20.14

10

Mental disorders due to use of illegal substances

8 925
(6 430–11 601)

3.0

0.8

-13.44

10

Diabetes mellitus

9 562
(6 448–13 126)

2.9

11.9

-2.7

All causes

299 263
(222 267–387 717)

100

15.74

-1.6

All causes

334 592
(249 070–431 502)

100

11.34

-0.6

1Years lived with disability (YLDs) with 95 % uncertainty intervals (UI)

2Percentage of total YLDs

3Percentage change 2006–2016 in numbers and age-adjusted rates

4Change significant at 5 % level

There was a consistent increase in the absolute number of years lived with disability in the population over the period 2006–2016, but little change in age-adjusted rates. Exceptions were a reduction in age-adjusted rates for mental disorders due to the use of illegal substances for men, and a reduction in ‘other musculoskeletal disorders’ for women.

The leading causes of disability-adjusted life years in Norway in 2016 were generally similar for men and women (Table 4). Seven of the ten most important disease groups were common to both sexes, including cardiovascular disease, lung cancer, dementia, and low back and neck pain. However, in women, migraine, anxiety and depression were also among the leading causes of disability-adjusted life years, whereas in men, substance use disorders, fall-related injuries and chronic obstructive pulmonary disease were high on the list. In men, only two of the ten leading causes of disability-adjusted life years resulted exclusively from years lived with disability (low back and neck pain, and sense organ diseases), whereas in women five out of ten conditions did so.

Table 4

Disease burden in Norway 2016. The ten leading causes of disability-adjusted life years1 (DALYs) in 2016 and changes over the period 2006–16

Men

Women

Change4 (%)

Change4 (%)

Number DALYs2
(95 % UI)

Percentage3 (%)

Percentage YLLs (%)

Number

Age-adjusted

Number DALYs2
(95 % UI)

Percentage (%)

Percentage3 YLLs (%)

Number

Age-adjusted

1

Ischaemic heart disease

56 654
(49 138–63 388)

9.0

90.5

-13.55

-29.65

1

Low back and neck pain

53 351
(37 570–70 603)

9.1

0.0

17.95

4.4

2

Low back and neck pain

45 061
(31 622–60 501)

7.2

0.0

12.65

-4.3

2

Ischaemic heart disease

32 927
(28 668–37 359)

5.6

89.4

-19.85

-28.25

3

Cancer of the trachea, bronchus and lung

23 322
(19 653–27 150)

3.7

98.3

-3.4

-23.95

3

Alzheimer’s disease and other forms of dementia

28 878
(23 877–34 957)

4.9

77.8

4.4

-2.7

4

Diseases of the skin and subcutaneous tissue

22 744
(15 582–32 236)

3.6

2.6

15.75

1.7

4

Diseases of the skin and subcutaneous tissue

27 618
(18 934–39 175)

4.7

2.2

12.5

1.6

5

Cerebrovascular disease

21 649
(18 614–
24 825)

3.4

72.1

-6.6

-23.45

5

Migraine

25 611
(16 595–
35 874)

4.4

0.0

12.75

0.9

6

Mental disorders due to use of illegal substances

20 278
(16 688–23 804)

3,2

56.0

1.0

-13.65

6

Cerebrovascular disease

21 558
(18 393–24 716)

3.7

68.4

-15.75

-22.55

7

Chronic obstructive pulmonary disease

20 203
(17 700–22 899)

3.2

71.9

6.1

-14.05

7

Depressive disorders

21 322
(14 715–28 906)

3.7

0.0

18.05

5.0

8

Fall-related injuries

18 750
(14 204–24 270)

3.0

29.4

14.55

-3.5

8

Anxiety disorders

19 682
(13 940–26 696)

3.4

0.0

11.55

-0.3

9

Sense organ diseases

18 655
(12 648–26 725)

3.0

0.0

19.75

-1.0

9

Sense organ diseases

18 838
(12 832–26 538)

3.2

0.0

10.25

-1.1

10

Alzheimer’s disease and other forms of dementia

17 768
(14 335–21 899)

2.8

78.9

16.65

-3.3

10

Cancer of the trachea, bronchus and lung

18 098
(15 335–21 177)

3.1

98.1

8.2

-10.7

All causes

628 711
(535 366–718 986)

100

52.4

6.2

-11.25

All causes

583 662
(493 252–685 906)

100

42.7

3.4

-7.45

1The sum of years of life lost (YLLs) plus years lived with disability (YLDs) is known as disability-adjusted life years (DALYs)

2Number of disability-adjusted life years (DALYs) with 95 % uncertainty intervals (UI)

3Percentage of total DALYs

4Percentage change over 2006–2016 in numbers and age-adjusted rates

5Change significant at 5 % level

Figure 1 shows the distribution, by age, of disease burden in the form of deaths, years of life lost, years lived with disability, and disability-adjusted life years, in 2016. Cancer was an important cause of death from the age of 40–50, whereas cardiovascular disease and dementia dominated in the oldest age groups. Accidents, overdoses and suicides were leading causes of years of life lost in adolescents and adults up to the age of 40, whereas cancer was more prominent for those between 40 and 80 years of age. In Norway, most of those who die, including those who die prematurely resulting in years of life lost, are over the age of 60–70 years. However, the number of years lived with disability is already considerable from the age of 10–20 years and remains high throughout the lifespan. Mental disorders become important from the age of about 10, for example, and musculoskeletal disorders from the age of about 20.

Figure 1 Disease burden in Norway 2016, estimates from the GBD project. All age groups are represented by columns, although not all of these are labelled underneath (e.g. 10–14 lies in between 5–9 and 15–19). Other group 1 diseases = HIV/AIDS and tuberculosis, neglected tropical diseases and malaria, neonatal disorders and others.

Discussion

The disease burden in Norway in 2016 was dominated by non-communicable diseases. Cardiovascular disease, cancer, chronic obstructive pulmonary disease and dementia were leading causes of years of life lost among both sexes. Suicide was also a significant cause of years of life lost, especially for men. Years lived with disability accounted for 48 % of the disease burden in men and 57 % in women. Musculoskeletal and mental disorders in particular were important contributors to this. Although age-adjusted rates for many conditions that lead to years of life lost have decreased over the last ten years, there has been little change in the rates for conditions that primarily result in years lived with disability.

As a result of population growth and ageing, there was an overall increase in the absolute burden of disease in Norway in the period 2006–16, measured in the number of disability-adjusted life years.

However, there was a decrease in the number of years of life lost from cardiovascular disease, which was a major cause of death and years of life lost among both sexes, and the same applied to the age-adjusted rates. This is most likely a result of beneficial lifestyle changes in the Norwegian population in recent years, in addition to progress in the prevention and treatment of cardiovascular disease (19).

For lung cancer and chronic obstructive pulmonary disease, the smoking-related causes of death, the pattern was somewhat different for men and women. There is a long latency from reduced smoking in the population to a visible effect in the form of a reduction in smoking-related causes of death, and there has been a phase shift in the smoking epidemic for men and women (20). For men, the age-adjusted rates for years of life lost to lung cancer and chronic obstructive pulmonary disease fell in the period 2006–16, while there was no definite change in the rates for women. Nor were there any significant changes in the number of years of life lost to lung cancer or chronic obstructive pulmonary disease for either men or women in the period.

The trend in years lived with disability was generally not positive in the period 2006–16. For both men and women, the total number of years lived with disability (non-fatal health loss) due to low back and neck pain, anxiety, depression, fall-related injuries and migraine increased, while the age-adjusted rates were stable. This indicates that the absolute increase may be explained by population growth and/or ageing – not by an increase in illness among people generally. On the other hand, stable age-adjusted rates indicate that we have not become more adept at preventing or treating these conditions, which account for a large and growing proportion of the burden of disease in the Norwegian population.

Despite the fact that women had more years lived with disability than men in 2016, men had a larger total disease burden. Since the reference mortality table used to calculate years of life lost in the GBD project is the same for both sexes, and men generally have a shorter life expectancy than women, men lose more years of life. For example, women and men had approximately the same number of deaths due to ischaemic heart disease in 2016, but women lost significantly fewer years of life because men die of cardiovascular disease at an earlier age than women.

The burden of disease is to a large extent caused by the same disease groups in men and women. Mental and substance use disorders, for example, together accounted for an approximately equal proportion of years lived with disability in men and women, 13 % and 12 % respectively. While anxiety and depression were the predominant causes in women, men were affected to a greater extent by substance use disorders.

One of the major innovations of the GBD project is the fact that it highlights years lived with disability in a population. Conditions that people suffer but do not die from are often invisible in traditional health and cause of death statistics. The disease burden from such conditions is analysed in various ways in different academic communities and disciplines, and this makes cross-comparisons very challenging. The GBD project attempts to quantify years lived with disability using one shared methodology, so that they can be measured on the same scale as years of life lost. It may well come as a surprise to many that a little more than half (52 %) of the disease burden in the Norwegian population in 2016 could be ascribed to years lived with disability.

Conclusion

The GBD project is an international epidemiological project. Estimates of the burden of disease, injury and risk factors for the years from 1990 onward are updated annually, for 195 countries and territories worldwide, for both sexes and all age groups. This provides an overview of the health of populations which in practice is impossible to obtain for any single country alone. In 2016, the burden of disease in Norway was dominated by non-communicable diseases such as cardiovascular disease, low back and neck pain, cancer, dementia and mental disorders. Although the last decade has shown positive developments for conditions that lead to years of life lost, particularly for cardiovascular diseases, the same trend has not been observed for conditions that generally result in years lived with disability.

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