In this study, widowers were shown to have a significantly lower survival rate compared with an age-matched control group and the difference in mortality rate increased over the period of the study period. The lower survival rate for the widowers was also apparent when comparing them to the general population of age-matched men. Common lifestyle risk factors could not be excluded as a contributing factor for the differences in mortality risk.
The study documents a survival analysis of all Icelandic widowers aged 30-75 years at the time of their wife's death. The widowers were followed up for 6 to 9 years. The mortality risk in the widowers' group was compared to that of randomly selected, age-matched controls, as well as to the mortality risk in the general population.
The present study was an extension of an epidemiological nation-wide study assessing widowers' psychological and physiological well-being and comparing them to a group of age-matched married men. Parts of that study have been previously published [32
It soon became apparent during the follow-up period of the original study group that the number of widowers who died prior to follow-up exceeded the death rate in the control group. Thus, this study was designed, and a decision was made to follow the groups over time.
Baseline (demographic) information
The baseline information presented in Table was only available from the responding participants in the primary epidemiological study, comprised of 61% (216) of the widowers and 56% (199) of the controls.
Comparing the demographic data between the groups showed that the groups were indeed very similar (Table ). There was no indication that the 14 widowers (baseline information not available) who had died before the time of selection of the control group were significantly different from the rest of the widowers regarding the assessed demographic variables or that including them would compromise the comparability between the widowers and controls.
Comparing survival estimates
In the comparison between the control group and the widowers presented in Table , the 14 widowers who had died before the selection date for the control group were included. Information from Table shows an increased mortality in the widowers' group and that it was statistically significant compared to that of the control group.
In Table , we compare survival in the general population of age-matched men with survival in the widowers' group, including the 14 widowers who had died during the 3-year period (1999-2001). The differences in crude survival estimates increased over the years (Table ). The relative survival of widowers and the general population also showed a progressive increase in mortality in the widowers' group (Table ). However, as expected the 95% confidence interval in the relative survival analysis for this comparison was only bordering on statistical significance (Table ). There were several problems with comparing the widowers with all aged-matched men from the general population (Table ). The general population also included the widowers. In a country with a small population this may have some (although small) effect on the comparison. More importantly, the general population data was comprised of all men, including those who had been chronically ill for a long time.
The effect of remarriage (or living with another woman) among widowers (2%) or the widowed among the controls (4%) most probably did not affect the results since there were very few of these cases (not in table).
Other studies on widowhood mortality
Increased probability of death amongst widows and widowers has been found in bereaved men and women of all ages around the world, using cross-sectional and longitudinal data, with and without covariate controls, and diverse statistical methodologies [9
]. Some studies have found an elevated mortality risk for bereaved individuals but no effects of covariates on the association between widowhood and mortality, which indicates that bereavement does not necessarily have a causal effect on survival [16
]. An empirical study of spousal bereavement in southern Sweden revealed that widowers in general were found to have a higher relative mortality than widows. In that study, the effects of bereavement decreased over time [40
There is limited data in the literature addressing why widowed people have a higher mortality risk compared with other age- and gender-matched groups [3
]. Many potential risk factors are still under-researched [2
]. Two recent epidemiological studies assessing increased mortality after spousal death reported strong indications that lifestyle-related diseases may, to a large extent, explain the observed increased mortality in the wives [3
]. The effects of bereavement on mortality was investigated in all widowed people in Sweden from 1968 to 1978, showing a significant increase in widowers' mortality during the first 3 months after bereavement (up by 48%) and excess mortality at a lower level for 11 years following spousal loss. Lifestyle factors could not be excluded as a possible explanation for excess mortality among widowers and widows [29
]. A Spanish study covered all individuals 25 years and older who died in Spain in 1991. The mortality risk was in all cases higher in single and widowed persons compared to married persons [42
]. From Denmark, a comparative study of losing a spouse and losing a co-twin showed a greater relative increase in mortality amongst the widowers during the first year. However, after the first year, the surviving twins' mortality risk became higher than that of the widowers [43
]. A prospective study of mortality from Finland reported an excessive mortality risk for both widows and widowers, but the relative mortality risk was higher for the widowers. They concluded that distress due to bereavement may have been directly related to increased mortality during the first months of bereavement, but that this effect appeared to be relatively small [6
]. Another Finnish epidemiological study reported an elevated relative mortality risk immediately after bereavement [4
Overall, it appears that studies on mortality in widowed people show an increased risk of mortality. Widowers appear to have a relatively higher mortality risk than widows. There may be a distress-related factor explaining some of this increase in mortality risk, but that appears to be a short-term effect. Shared lifestyle risk factors have been suggested as a possible explanation for long-term increased mortality in widowhood.
Causes of death
Several studies have shown that people living together over a long period of time tend to have similar health risk behaviors [11
]. Most cancers and cardiovascular diseases are strongly related to lifestyle risk factors such as smoking, alcohol use, diet, lack of physical activity, overweight and obesity [19
Although we did not assess lifestyle in the present study, we were able to identify all causes of death in all subjects, according to WHO's International Classification of Diseases. A conservative approach was chosen to compare causes of death in 3 groups, cancer, cardiovascular diseases and other causes (Table ). There was an overrepresentation of cancer deaths for widowers' wives in all age groups (not in table), but there were very few deceased wives in the control group (13) and, therefore, comparison was difficult. Cancer deaths follow a similar pattern between all age groups when comparing widowers and controls (Table ), and the same is true for cardiovascular diseases.
Probably the most interesting finding from the cause-of-death analysis was the fact that in the control group there were no cases where both couples had died during the follow-up period, in contrast to 17.3% (64/371) of couples in the widowers' group.
The main strength of our study is that it was based on a total national sample of widowers, comprised of all widowers up to the age of 75 during a 3-year period. In addition, we were able to compare the mortality risks, both with a control group of married men as well as population-based statistics for all men in Iceland during a 6-to-9 year follow-up. Both approaches have limitations and strengths. Unfortunately, we were unable to relate causes of death to particular lifestyle factors due to the study design, since lifestyle assessment was not a part of the original study.
An important weakness of the present study was that it was not a mortality study from the start. Also, due to anonymity the information obtained in the questionnaire could not be used to analyze risk factors.
Public health implications
Assessing and describing the health consequences of widowhood is an understudied area of public health research. Understanding how widowhood may impact health and survival may help us to better understand how to support people in these situations.