Mortality in Norway and Sweden during the COVID-19 pandemic 2020-22: A comparative study

BACKGROUND

Norway and Sweden picked two different ways to mitigate the dissemination of the SARS-CoV-2 virus. Norway introduced the strictest lockdown in Europe with strict border controls and intense virus tracking of all local outbreaks while Sweden did not. That resulted in 477 COVID-19 deaths (Norway) and 9737 (Sweden) in 2020, respectively.

METHODS

Weekly number of COVID-19 related deaths and total deaths for 2020-22 were collected as well as weekly number of deaths for 2015-19 which were used as controls when calculating excess mortality. During the first 12-18 months with high rate of virus transmission in the society, excess mortality rates were used as substitute for COVID-19 deaths. When excess mortality rates later turned negative because of mortality displacement, COVID-19 deaths adjusted for bias due to overreporting were used.

RESULTS

There were 17521 COVID-19 deaths in Sweden and 4272 in Norway in the study period. The rate ratio (RR) of COVID-19 related deaths in Sweden vs. Norway to the end of week 43, 2022, was 2.11 (95% CI 2.05-2.19). RR of COVID-19 related deaths vs. excess number of deaths were 2.5 (Sweden) and 1.3 (Norway), respectively. RR of COVID-19 deaths in Sweden vs. Norway after adjusting for mortality displacement and lockdown, was 1.35 (95% CI 1.31-1.39), corresponding to saving 2025 life in Norway. If including all deaths in 2022, RR= 1.28 (95% CI 1.24-1.31).

CONCLUSIONS

Both COVID-19 related mortality and excess mortality rates are biased estimates. When adjusting for bias, mortality differences declined over time to about 30% higher mortality in Sweden after 30 months with pandemics.

Quality-of-life effects of screening mammography in Norway

Mammography screening may save women from dying of breast cancer, although it has not been shown to reduce all-cause mortality. Screening also leads to overdiagnosis and many false positive mammograms aggravating women's quality-of-life. Quality adjusted life years (QALY) analyses of mammography screening have so far, calculated life years gained assuming that all prevented breast cancer deaths translate into a reduction in all-cause mortality. We calculated net QALYs in two hypothesized cohorts of 100,000 Norwegian women; one screened biennially from age 50 to 69 years and one not screened. We followed both cohorts to age 85 years. We used EQ-5D and an alternative equity weighted QALY instrument to estimate utility losses. In the screening cohort, we assumed 20% false positive tests during screening, different levels of overdiagnosis (20-75%) and different levels of breast cancer mortality reduction (10-30%). We assumed that reductions in breast cancer mortality only to a limited extent (20, 50 or 80%), resulted in reductions in all-cause mortality. We calculated both undiscounted and discounted (4%) QALYs. Assuming that 50% of the reduction in breast cancer mortality translated to a reduction in all-cause mortality and using estimated levels of benefits and harms in modern screening programs (50-75% overdiagnosis and 10% reduction in breast cancer mortality), undiscounted equity weighted QALY loss varied from 437 to 875 per 100,000 women. Using the levels of benefit and harms as reported in 30-40 years old randomized trials (30% overdiagnosis and 15% reduction in breast cancer mortality), undiscounted equity weighted QALY gain was 535 per 100,000. Net QALY in modern mammography screening in Norway is negative. Results could also be representative for Sweden, Denmark, UK and the US.

Managing suicidality within specialized care: A randomized controlled trial

BACKGROUND

Suicide prevention is a core task in mental health services. Our objective was to determine whether Collaborative Assessment and Management of Suicidality (CAMS) reduced suicidal thoughts and behaviors and mental health distress more effectively than treatment as usual (TAU) in a heterogeneous patient population within specialized mental health care services.

METHODS

In this observer-blinded pragmatic randomized controlled trial participants who scored 13 or above on Beck's Scale for Suicide Ideation-Current (BSSI-C) were included from seven in- and outpatient units. Primary outcome was suicidal ideation (BSSI-C). Secondary outcomes were mental health distress measured by the Outcome Questionnaire-45, and suicidal behaviors measured by the Suicide Attempt Self-Injury Count. Patients were assessed at baseline and after 6 and 12 months.

RESULTS

The final intent-to-treat analyses included 78 participants (mean age 35.9 years, SD = 14.5, 41 females). The majority were depressed (65%), had a secondary diagnosis (73%) and 32% suffered from borderline personality disorder or borderline traits. After 6 months, CAMS participants reported lower levels of suicidal ideation compared to TAU (β = -4.29, 95% CI = -8.32 to -0.27, p = .036). Larger changes in mental health distress were observed for CAMS participants after 6 months (β = -11.87, 95% CI = -22.99 to -0.76, p = .036) and 12 months (β = -13.70, 95% CI = -24.88 to -2.51, p = .017).

LIMITATIONS

The modest sample size rendered the trial unable to detect small between-group differences.

CONCLUSIONS

CAMS reduced suicidal ideation and mental health distress more efficiently than TAU in a heterogeneous patient population within specialized care.

Breast Cancer Screening in Denmark: A Cohort Study of Tumor Size and Overdiagnosis

BACKGROUND

Effective breast cancer screening should detect early-stage cancer and prevent advanced disease.

OBJECTIVE

To assess the association between screening and the size of detected tumors and to estimate overdiagnosis (detection of tumors that would not become clinically relevant).

DESIGN

Cohort study.

SETTING

Denmark from 1980 to 2010.

PARTICIPANTS

Women aged 35 to 84 years.

INTERVENTION

Screening programs offering biennial mammography for women aged 50 to 69 years beginning in different regions at different times.

MEASUREMENTS

Trends in the incidence of advanced (>20 mm) and nonadvanced (≤20 mm) breast cancer tumors in screened and nonscreened women were measured. Two approaches were used to estimate the amount of overdiagnosis: comparing the incidence of advanced and nonadvanced tumors among women aged 50 to 84 years in screening and nonscreening areas; and comparing the incidence for nonadvanced tumors among women aged 35 to 49, 50 to 69, and 70 to 84 years in screening and nonscreening areas.

RESULTS

Screening was not associated with lower incidence of advanced tumors. The incidence of nonadvanced tumors increased in the screening versus prescreening periods (incidence rate ratio, 1.49 [95% CI, 1.43 to 1.54]). The first estimation approach found that 271 invasive breast cancer tumors and 179 ductal carcinoma in situ (DCIS) lesions were overdiagnosed in 2010 (overdiagnosis rate of 24.4% [including DCIS] and 14.7% [excluding DCIS]). The second approach, which accounted for regional differences in women younger than the screening age, found that 711 invasive tumors and 180 cases of DCIS were overdiagnosed in 2010 (overdiagnosis rate of 48.3% [including DCIS] and 38.6% [excluding DCIS]).

LIMITATION

Regional differences complicate interpretation.

CONCLUSION

Breast cancer screening was not associated with a reduction in the incidence of advanced cancer. It is likely that 1 in every 3 invasive tumors and cases of DCIS diagnosed in women offered screening represent overdiagnosis (incidence increase of 48.3%).

PRIMARY FUNDING SOURCE

None.

Differing Procedures for Recording Mortality Statistics in Scandinavia

BACKGROUND

There may be various reasons for differences in suicide rates between countries and over time within a country. One reason can be different registration practices.

AIMS

The purpose of this study was to describe and compare the present procedures for mortality and suicide registration in the three Scandinavian countries and to illustrate potential sources of error in the registration of suicide.

METHOD

Information about registration practices and classification procedures was obtained from the cause of death registers in Norway, Sweden, and Denmark. In addition, we received information from experts in the field in each country.

RESULTS

Sweden uses event of undetermined intent more frequently than Denmark does, and Denmark more frequently than Norway. There seems to be somewhat more uncertainty among deaths classified as ill-defined and unknown cause of mortality in Norway, compared with the other two countries. Sweden performs more forensic autopsies than Norway, and Norway more than Denmark. In Denmark, in cases of a suspected unnatural manner of death, a thorough external examination of the deceased is performed.

CONCLUSION

Differences in the classification of causes of death and in postmortem examinations exist in Scandinavian countries. These differences might influence the suicide statistics in Scandinavia.

Accidents and undetermined deaths: re-evaluation of nationwide samples from the Scandinavian countries

Background

National mortality statistics should be comparable between countries that use the World Health Organization’s International Classification of Diseases. Distinguishing between manners of death, especially suicides and accidents, is a challenge. Knowledge about accidents is important in prevention of both accidents and suicides. The aim of the present study was to assess the reliability of classifying deaths as accidents and undetermined manner of deaths in the three Scandinavian countries and to compare cross-national differences.

Methods

The cause of death registers in Norway, Sweden and Denmark provided data from 2008 for samples of 600 deaths from each country, of which 200 were registered as suicides, 200 as accidents or undetermined manner of deaths and 200 as natural deaths. The information given to the eight experts was identical to the information used by the Cause of Death Register. This included death certificates, and if available external post-mortem examinations, forensic autopsy reports and police reports.

Results

In total, 69 % (Sweden and Norway) and 78 % (Denmark) of deaths registered in the official mortality statistics as accidents were confirmed by the experts. In the majority of the cases where disagreement was seen, the experts reclassified accidents to undetermined manner of death, in 26, 25 and 19 % of cases, respectively. Few cases were reclassified as suicides or natural deaths. Among the extracted accidents, the experts agreed least with the official mortality statistics concerning drowning and poisoning accidents. They also reported most uncertainty in these categories of accidents. In a second re-evaluation, where more information was made available, the Norwegian psychiatrist and forensic pathologist increased their agreement with the official mortality statistics from 76 to 87 %, and from 85 to 88 %, respectively, regarding the Norwegian and Swedish datasets. Among the extracted undetermined deaths in the Swedish dataset, the two experts reclassified 22 and 51 %, respectively, to accidents.

Conclusion

There was moderate agreement in reclassification of accidents between the official mortality statistics and the experts. In the majority of cases where there was disagreement, accidents were reclassified as undetermined manner of death, and only a small proportion as suicides.

Are suicide deaths under-reported? Nationwide re-evaluations of 1800 deaths in Scandinavia

OBJECTIVE

Valid mortality statistics are important for healthcare planning and research. Suicides and accidents often present a challenge in the classification of the manner of death. The aim of this study was to analyse the reliability of the national suicide statistics by comparing the classification of suicide in the Scandinavian cause of death registers with a reclassification by 8 persons with different medical expertise (psychiatry, forensic pathology and public health) from each of the 3 Scandinavian countries.

METHODS

The cause of death registers in Norway, Sweden and Denmark retrieved available information on a sample of 600 deaths in 2008 from each country. 200 were classified in the registers as suicides, 200 as accidents or undetermined and 200 as natural deaths. The reclassification comprised an assessment of the manner and cause of death as well as the level of certainty.

RESULTS

In total, 81%, 88% and 90% of deaths registered as suicide in the official mortality statistics were confirmed by experts using the Swedish, Norwegian and Danish data sets, respectively. About 3% of deaths classified as accidents or natural deaths in the cause of death registers were reclassified as suicides. However, after a second reclassification based on additional information, 9% of the natural deaths and accidents were reclassified as suicides in the Norwegian data set, and 21% of the undetermined deaths were reclassified as suicides in the Swedish data set. In total, the levels of certainty of the experts were 87% of suicides in the Norwegian data set, 77% in the Swedish data set and 92% in Danish data set; the uncertainty was highest in poisoning suicides.

CONCLUSIONS

A high percentage of reported suicides were confirmed as being suicides. Few accidents and natural deaths were reclassified as suicides. Hence, reclassification did not increase the overall official suicide statistics of the 3 Scandinavian countries.

Breast cancer incidence and menopausal hormone therapy in Norway from 2004 to 2009: a register-based cohort study

In Norway, the breast cancer incidence increased by 50% in the 1990s, during a period with initiation of mammography screening as well as a fourfold increase in use of menopausal hormone therapy (HT). After 2002, the HT use has dropped substantially; however, the breast cancer incidence has declined only marginally. How much mammography screening contributed to the breast cancer incidence increase in the 1990s compared with HT use and specifically different types of HT use, has thus been discussed. Whether HT affects the incidence of subtypes of breast cancer differently has also been questioned. We have linked individual data from several national registries from 2004 to 2009 on 449,717 women aged 50–65 years. 4597 cases of invasive cancer and 681 cases of ductal carcinoma in situ (DCIS) were included in the analysis. We used Cox regression to estimate hazard ratio (HR) as a measure of the relative risk of breast cancer associated with use of HT. The HRs associated with prescriptions of HT for more than 1 year were 2.06 (1.90–2.24) for estrogen and progesterone combinations, 1.03 (0.85–1.25) for systemic estrogens, and 1.23 (1.01–1.51) for tibolone. Invasive lobular carcinoma was more strongly associated with use of estrogen and progesterone combinations, HR = 3.10 (2.51–3.81), than nonlobular carcinoma, HR = 1.94 (1.78–2.12). The corresponding value for DCIS was 1.61 (1.28–2.02). We estimated the population attributable fraction to 8.2%, corresponding to 90 breast cancer cases in 2006 indicating that HT use still caused a major number of breast cancer cases.

Lead-time models should not be used to estimate overdiagnosis in cancer screening

Lead-time can mean two different things: Clinical lead-time is the lead-time for clinically relevant tumors; that is, those that are not overdiagnosed. Model-based lead-time is a theoretical construct where the time when the tumor would have caused symptoms is not limited by the person's death. It is the average time at which the diagnosis is brought forward for both clinically relevant and overdiagnosed cancers. When screening for breast cancer, clinical lead-time is about 1 year, while model-based lead-time varies from 2 to 7 years. There are two different methods to calculate overdiagnosis in cancer screening--the excess-incidence approach and the lead-time approach--that rely on two different lead-time definitions. Overdiagnosis when screening with mammography has varied from 0 to 75 %. We have explained that these differences are mainly caused by using different definitions and methods and not by variations in data. High levels of overdiagnosis of cancer have usually been explained by detection of many slow-growing tumors with long lead-times. This theory can be tested by studying if slow-growing tumors accumulate in the absence of screening, which they don't. Thus, it is likely that the natural history of many subclinical cancers is spontaneous regression.

Overdiagnosis of breast cancer after 14 years of mammography screening

BACKGROUND

In 2004 we wrote in Tidsskriftet that mammography screening resulted in massive over-diagnosis and over-treatment of breast cancer. Our study was criticised because we had only five years of follow-up time and did not take account of the fact that increased use of hormone replacement therapy could lead to more breast cancer. We have now been screening women for 14 years, and during a period when the use of hormones has fallen by 70 %.

MATERIAL AND METHOD

Age-specific incidence rates, detection rates and interval rates for breast cancer in the period 1991-2009 have been computed for 40-79 year-old women. Incidence trends have been calculated using Poisson regression.

RESULTS

The incidence of breast cancer in the age group 40-49 was stable throughout the period, but rose by 50 % in the age group 50-69 years immediately after the start of screening. There was no significant reduction in the incidence of breast cancer in the age group 70-74. The number of new cases of breast cancer in the period increased from around 2000 to 2750. About 300 cases of ductal carcinoma in situ (DCIS) were also diagnosed. Today a total of some 1050 more women have been diagnosed than before screening started. Our calculations indicate that in the absence of screening, around 800 of these women would never have become breast cancer patients.

INTERPRETATION

The figures from 14 years of mammography screening indicate that all increase in the incidence of breast cancer is due to over-diagnosis: findings of tumours that in the absence of screening would never have given rise to clinical illness.

Natural history of breast cancers detected in the Swedish mammography screening programme: a cohort study

BACKGROUND

The natural history of screen-detected breast cancers is not well understood. A previous analysis of the incidence change during the introduction of the Norwegian screening programme in the late 1990s suggested that the natural history of many screen-detected invasive breast cancers is to regress spontaneously but the study was possibly confounded by use of hormone replacement therapy in the population. We did a similar analysis of data collected during an earlier period when few women were exposed to hormone replacement therapy.

METHODS

We compared cumulative breast cancer incidence in age-matched cohorts of women living in seven Swedish counties before and after the initiation of public mammography screening between 1986 and 1990. Women aged 40-49 years were invited to screening every year and women aged 50-74 years were invited every 2 years. A screened group including all women aged 40-69 years (n=328,927) was followed-up for 6 years after the first invitation to the programme. A control group including all women in the same age range (n=317,404) was also followed-up for 6 years--4 years without screening and 2 years when they entered the screening programme. Screening attendance was much the same in both groups (close to 80%). Counts of incident invasive breast cancers were obtained from the Swedish Cancer Registry (in-situ cancers were excluded).

FINDINGS

Before the age-matched controls were invited to be screened at the end of their follow-up period, the 4-year cumulative incidence of invasive breast cancer was significantly higher in the screened group (982 per 100,000) than it was in the control group (658 per 100,000) (relative risk [RR] 1·49, 95% CI 1·41-1·58). Even after prevalence screening in the control group, the screened group had higher 6-year cumulative incidence of invasive breast cancer (1443 per 100,000 vs 1269 per 100,000; RR 1·14, 1·10-1·18).

INTERPRETATION

Because the cumulative incidence among controls did not reach that of the screened group, we believe that many invasive breast cancers detected by repeated mammography screening do not persist to be detected by screening at the end of 6 years, suggesting that the natural course of many of the screen-detected invasive breast cancers is to spontaneously regress.

FUNDING

None.

An investigation of the apparent breast cancer epidemic in France: screening and incidence trends in birth cohorts

BACKGROUND

Official descriptive data from France showed a strong increase in breast-cancer incidence between 1980 to 2005 without a corresponding change in breast-cancer mortality. This study quantifies the part of incidence increase due to secular changes in risk factor exposure and in overdiagnosis due to organised or opportunistic screening. Overdiagnosis was defined as non progressive tumours diagnosed as cancer at histology or progressive cancer that would remain asymptomatic until time of death for another cause.

METHODS

Comparison between age-matched cohorts from 1980 to 2005. All women residing in France and born 1911-1915, 1926-1930 and 1941-1945 are included. Sources are official data sets and published French reports on screening by mammography, age and time specific breast-cancer incidence and mortality, hormone replacement therapy, alcohol and obesity. Outcome measures include breast-cancer incidence differences adjusted for changes in risk factor distributions between pairs of age-matched cohorts who had experienced different levels of screening intensity.

RESULTS

There was an 8-fold increase in the number of mammography machines operating in France between 1980 and 2000. Opportunistic and organised screening increased over time. In comparison to age-matched cohorts born 15 years earlier, recent cohorts had adjusted incidence proportion over 11 years that were 76% higher [95% confidence limits (CL) 67%, 85%] for women aged 50 to 64 years and 23% higher [95% CL 15%, 31%] for women aged 65 to 79 years. Given that mortality did not change correspondingly, this increase in adjusted 11 year incidence proportion was considered as an estimate of overdiagnosis.

CONCLUSIONS

Breast cancer may be overdiagnosed because screening increases diagnosis of slowly progressing non-life threatening cancer and increases misdiagnosis among women without progressive cancer. We suggest that these effects could largely explain the reported "epidemic" of breast cancer in France. Better predictive classification of tumours is needed in order to avoid unnecessary cancer diagnoses and subsequent procedures.

Effect of mammography screening on surgical treatment for breast cancer in Norway: comparative analysis of cancer registry data

OBJECTIVE

To determine the effect of mammography screening on surgical treatment for breast cancer.

DESIGN

Comparative analysis of data from Norwegian cancer registry.

SETTING

Mammography screening, Norway (screening of women aged 50-69 was introduced sequentially from 1996 to 2004).

PARTICIPANTS

35,408 women aged 40-79 with invasive breast cancer or ductal carcinoma in situ treated surgically from 1993 to 2008.

MAIN OUTCOME MEASURES

Rates of breast surgery (mastectomy plus breast conserving treatment) and rates of mastectomy for three age groups of women: 40-49, 50-69, and 70-79. Changes in rates from pre-screening period (1993-5) to introduction of screening phase (1996-2004) and then to screening period (2005-8) are presented as hazard ratios in invited and non-invited women.

RESULTS

The annual rate for breast surgery from the pre-screening period (1993-5) to screening period (2005-8) in Norway increased by 70% (hazard ratio 1.70, 95% confidence interval 1.62 to 1.78), from 180 to 305 per 100,000 women in the invited age group (50-69 years). In the younger, non-invited age group (40-49 years), however, the increase was only 8% (1.08, 1.00 to 1.16), from 133 to 144 per 100,000 women per year, whereas in the older, non-invited age group (70-79 years) the rate decreased by 8% (0.92, 0.86 to 1.00), from 227 to 214 per 100,000 women per year. The rates for mastectomy decreased similarly from the pre-screening period to screening period in invited and non-invited women. From the pre-screening period to the introduction phase of screening (1996-2004), however, the annual mastectomy rate in women aged 50-69 invited to screening increased by 9% (1.09, 1.03 to 1.14), from 156 to 167 per 100,000 women, and in the younger non-invited women declined by 17% (0.83, 0.78 to 0.90), from 109 to 91 per 100,000 women. In consequence, the mastectomy rate was 31% (1.31, 1.20 to 1.43) higher in the invited than in the non-invited younger age group.

CONCLUSIONS

Mammography screening in Norway was associated with a noticeable increase in rates for breast cancer surgery in women aged 50-69 (the age group invited to screening) and also an increase in mastectomy rates. Although over-diagnosis is likely to have caused the initial increase in mastectomy rates and the overall increase in surgery rates in the age group screened, the more recent decline in mastectomy rates has affected all age groups and is likely to have resulted from changes in surgical policy.

Changes in mental health services and suicide mortality in Norway: an ecological study

Background

Mental disorders are strongly associated with excess suicide risk, and successful treatment might prevent suicide. Since 1990, and particularly after 1998, there has been a substantial increase in mental health service resources in Norway. This study aimed to investigate whether these changes have had an impact on suicide mortality.

Methods

We used Poisson regression analyses to assess the effect of changes in five mental health services variables on suicide mortality in five Norwegian health regions during the period 1990-2006. These variables included: number of man-labour years by all personnel, number of discharges, number of outpatient consultations, number of inpatient days, and number of hospital beds. Adjustments were made for sales of alcohol, sales of antidepressants, education, and unemployment.

Results

In the period 1990-2006, we observed a total of 9480 suicides and the total suicide rate declined by 26%. None of the mental health services variables were significantly associated with female or male suicide mortality in the adjusted analyses (p > 0.05). Sales of antidepressants (adjusted Incidence Rate Ratio = 0.98; 95% CI = 0.97-1.00) and sales of alcohol (adjusted IRR = 1.41; 95% CI = 1.18-1.72) were significantly associated with female suicide mortality; education (adjusted IRR = 0.86; 95% CI = 0.79-0.94) and unemployment (adjusted IRR = 0.91; 95% CI = 0.85-0.97) were significantly associated with male suicide mortality.

Conclusions

The adjusted analyses in the present study indicate that increased resources in Norwegian mental health services in the period 1990-2006 were statistically unrelated to suicide mortality.

The relationship between sales of SSRI, TCA and suicide rates in the Nordic countries

BACKGROUND

In the period 1990-2006, strong and almost equivalent increases in sales figures of selective serotonin re-uptake inhibitors (SSRIs) were observed in all Nordic countries. The sales figures of tricyclic antidepressants (TCAs) dropped in Norway and Sweden in the nineties. After 2000, sales figures of TCAs have been almost constant in all Nordic countries. The potentially toxic effect of TCAs in overdose was an important reason for replacing TCAs with SSRIs when treating depression. We studied whether the rapid increase in sales of SSRIs and the corresponding decline in TCAs in the period 1990-98 were associated with a decline in suicide rates.

METHODS

Aggregated suicide rates for the period 1975-2006 in four Nordic countries (Denmark, Finland, Norway and Sweden) were obtained from the national causes-of-death registries. The sales figures of antidepressants were provided from the wholesale registers in each of the Nordic countries. Data were analysed using Fisher's exact test and Pearson's correlation coefficient.

RESULTS

There was no statistical association (P = 1.0) between the increase of sales figures of SSRIs and the decline in suicide rates. There was no statistical association (P = 1.0) between the decrease in the sale figures of TCAs and change in suicide rates either.

CONCLUSIONS

We found no evidence for the rapid increase in use of SSRIs and the corresponding decline in sales of TCAs being associated with a decline in the suicide rates in the Nordic countries in the period 1990-98. We did not find any inverse relationship between the increase in sales of SSRIs and declining suicide rates in four Nordic countries.