Studies of tends in the relationship of marital status to mortality must consider the implications of general changes in mortality
James Scanlan, James P. Scanlan, Attorney at Law
7 November 2011
The study by Berntsen [1] found that between 1971 and 2007 among elderly Norwegian men and women relative differences in mortality by marital status increased for circulatory diseases but remained stable for cancer. The study also found that during the period examined deaths from circulatory disease decreased while deaths from cancer increased. But the study failed to consider the potential relationship of the patterns of relative differences in mortality and the overall changes in mortality rates.
For reasons related to the shapes of normal distributions of factors associated with experiencing an outcome, the rarer an outcome the greater tends to be the relative difference in experiencing it and the smaller tends to be the relative difference in avoiding it. Thus, as mortality declines, relative differences in mortality tend to increase while relative differences in survival tend to decrease. [2-6]
Berntsen examined patterns of changes in relative differences in mortality rates in terms of odds ratio. Patterns of changes in differences measured by odds ratios are the same whether one examines the odds of mortality or the odds of survival. But odds ratios tend also to be affected by changes in the overall prevalence of an outcome. Without belaboring the nuances of these effects (such as are discussed in the introductory material of reference 7 or illustrated in Figure 3 of reference 8), it suffices to say that mortality rates usually are in ranges where differences measured by odds ratios tend to behave like relative differences in mortality.
This is not to say that there occurred no changes in the comparative well-being of the various groups defined by marital status or even that all or most measures changed in way that the distributional forces tend to drive them. (The absence of a decrease in the relative difference in mortality from cancer during a period of increased cancer mortality in facts suggests otherwise.) The distributionally-driven patterns are only part of the story. The other part of the story, and that which is society’s actual concern, involves changes in the relationships of the risk distributions of the two groups. But in order to determine whether there occurred meaningful changes in the comparative well-being of various groups – that is, changes that are not functions of changes in the overall prevalence of an outcome – it is necessary to examine the actual rates. Such examination will allow one to cautiously draw inferences about meaningful changes either by identifying departures from the distributionally-driven patterns [1,8] or by deriving from the mortality rates of comparison groups the difference between means of the hypothesized underlying distributions.[7-9]
Unfortunately, Berntsen did not provide the actual rates with the study. Further exploration of the issue must examine the actual rates with recognition of the distributionally-driven patterns described above.
Berntsen posits a number of possible explanations for the perceived worsening of the comparative situation of the never married with respect to mortality from cardiovascular disease. None of these explanations is implausible. But it remains unknown whether such worsening in fact occurred.
References:
1. Berntsen KN. Trends in total and cause-specific mortality by marital status among elderly Norwegian men and women. BMC Public Health 2011; 11:537: http://www.biomedcentral.com/1471-2458/11/537
2. Scanlan JP. Can we actually measure health disparities? Chance 2006:19(2):47-51: http://www.jpscanlan.com/images/Can_We_Actually_Measure_Health_Disparities.pdf
3. Scanlan JP. Race and mortality. Society 2000;37(2):19-35: http://www.jpscanlan.com/images/Race_and_Mortality.pdf
5. Scanlan JP. The Misunderstood Relationship Between Declining Mortality and Increasing Racial and Socioeconomic Disparities in Mortality Rates, presented at the conference "Making a Difference: Is the Health Gap Widening?" sponsored by the Norwegian National Institute of Public Health, Oslo Norway, May 14, 2001: http://www.jpscanlan.com/images/Oslo_presentation.ppt
6. Scanlan’s Rule page of jpscanlan.com: http://jpscanlan.com/scanlansrule.html
7. Measures of Health Inequalities that are Unaffected by the Prevalence of an Outcome, presented at the 16th Nordic Demographic Symposium, Helsinki, Finland, June 5-7, 2008: http://jpscanlan.com/images/Scanlan_JP_NDS_Presentation_2R.ppt
8. Scanlan JP. Comparing the size of inequalities in dichotomous measures in light of the standard correlations between such measures and the prevalence of an outcome. Journal Review Jan. 14, 2008 (responding to Boström G, Rosén M. Measuring social inequalities in health – politics or science? Scan J Public Health 2003;31:211-215): http://journalreview.org/v2/articles/view/12850975.html
9. Solutions sub-page of Measuring Health Disparities page of jpscanlan.com: http://www.jpscanlan.com/measuringhealthdisp/solutions.html
Studies of tends in the relationship of marital status to mortality must consider the implications of general changes in mortality
7 November 2011
The study by Berntsen [1] found that between 1971 and 2007 among elderly Norwegian men and women relative differences in mortality by marital status increased for circulatory diseases but remained stable for cancer. The study also found that during the period examined deaths from circulatory disease decreased while deaths from cancer increased. But the study failed to consider the potential relationship of the patterns of relative differences in mortality and the overall changes in mortality rates.
For reasons related to the shapes of normal distributions of factors associated with experiencing an outcome, the rarer an outcome the greater tends to be the relative difference in experiencing it and the smaller tends to be the relative difference in avoiding it. Thus, as mortality declines, relative differences in mortality tend to increase while relative differences in survival tend to decrease. [2-6]
Berntsen examined patterns of changes in relative differences in mortality rates in terms of odds ratio. Patterns of changes in differences measured by odds ratios are the same whether one examines the odds of mortality or the odds of survival. But odds ratios tend also to be affected by changes in the overall prevalence of an outcome. Without belaboring the nuances of these effects (such as are discussed in the introductory material of reference 7 or illustrated in Figure 3 of reference 8), it suffices to say that mortality rates usually are in ranges where differences measured by odds ratios tend to behave like relative differences in mortality.
This is not to say that there occurred no changes in the comparative well-being of the various groups defined by marital status or even that all or most measures changed in way that the distributional forces tend to drive them. (The absence of a decrease in the relative difference in mortality from cancer during a period of increased cancer mortality in facts suggests otherwise.) The distributionally-driven patterns are only part of the story. The other part of the story, and that which is society’s actual concern, involves changes in the relationships of the risk distributions of the two groups. But in order to determine whether there occurred meaningful changes in the comparative well-being of various groups – that is, changes that are not functions of changes in the overall prevalence of an outcome – it is necessary to examine the actual rates. Such examination will allow one to cautiously draw inferences about meaningful changes either by identifying departures from the distributionally-driven patterns [1,8] or by deriving from the mortality rates of comparison groups the difference between means of the hypothesized underlying distributions.[7-9]
Unfortunately, Berntsen did not provide the actual rates with the study. Further exploration of the issue must examine the actual rates with recognition of the distributionally-driven patterns described above.
Berntsen posits a number of possible explanations for the perceived worsening of the comparative situation of the never married with respect to mortality from cardiovascular disease. None of these explanations is implausible. But it remains unknown whether such worsening in fact occurred.
References:
1. Berntsen KN. Trends in total and cause-specific mortality by marital status among elderly
Norwegian men and women. BMC Public Health 2011; 11:537: http://www.biomedcentral.com/1471-2458/11/537
2. Scanlan JP. Can we actually measure health disparities? Chance 2006:19(2):47-51:
http://www.jpscanlan.com/images/Can_We_Actually_Measure_Health_Disparities.pdf
3. Scanlan JP. Race and mortality. Society 2000;37(2):19-35: http://www.jpscanlan.com/images/Race_and_Mortality.pdf
4. Scanlan JP. Divining difference. Chance 1994;7(4):38-9,48: http://jpscanlan.com/images/Divining_Difference.pdf
5. Scanlan JP. The Misunderstood Relationship Between Declining Mortality and Increasing Racial and Socioeconomic Disparities in Mortality Rates, presented at the conference "Making a Difference: Is the Health Gap Widening?" sponsored by the Norwegian National Institute of Public Health, Oslo Norway, May 14, 2001: http://www.jpscanlan.com/images/Oslo_presentation.ppt
6. Scanlan’s Rule page of jpscanlan.com: http://jpscanlan.com/scanlansrule.html
7. Measures of Health Inequalities that are Unaffected by the Prevalence of an Outcome, presented at the 16th Nordic Demographic Symposium, Helsinki, Finland, June 5-7, 2008: http://jpscanlan.com/images/Scanlan_JP_NDS_Presentation_2R.ppt
8. Scanlan JP. Comparing the size of inequalities in dichotomous measures in light of the standard correlations between such measures and the prevalence of an outcome. Journal Review Jan. 14, 2008 (responding to Boström G, Rosén M. Measuring social inequalities in health – politics or science? Scan J Public Health 2003;31:211-215): http://journalreview.org/v2/articles/view/12850975.html
9. Solutions sub-page of Measuring Health Disparities page of jpscanlan.com: http://www.jpscanlan.com/measuringhealthdisp/solutions.html
Competing interests
None