In contrast, Vuorisalmi, Lintonen and Jylhä [ 6] reported both an age-comparative and global comparative item was a stronger predictor of mortality for males than females.
The current findings support this notion of age-sensitivity and extend it to the self-comparative item.
Manderbacka, Kareholt, Martikainen and Lundberg [ 5] found the predictive quality of global and age-comparative SRH items was dependent on gender, with the age-comparative item being a better predictor of mortality for males than females in simultaneous models.
For example, the age-comparative item may enhance health assessments due to a self-protective 'social downgrading' process [ 35], whereas the forced temporal aspect of the self-comparative item elicits more negative ratings as it makes recent negative changes in health more salient [ 36].
This comparison revealed that, overall, global SRH was the strongest predictor of mortality when taking into account the time-varying nature of the ratings across time, whilst the weakest association was with the self-comparative item.
It has been argued that the age-comparative item is not appropriate to use in older populations, or samples with a large age range, due to its sensitivity to age [ 6, 34, 38].
Even less attention has been paid to the self-comparative item, and the temporal reference point that is used in the few studies has been broad (i.e. ranging from 5 to 10 years previous).
In a study that compared a global, age-comparative and self-comparative (10 years previous) SRH items it was found that the predictive quality of the self-comparative item became less robust for males after longer follow up periods, whereas none of the SRH items were predictive of mortality in adjusted models for females after 3 and 7.5 year follow-ups [ 8].
However, with advanced health decline older adults may perceive that their health cannot get any worse, thus they may begin to rate their health as 'the same' as previous, placing an inherent limitation to the self-comparative item for providing unique mortality information over time.
In the few studies that have compared the determinants of global and comparative SRH items, the global measure has been found to be the most inclusive measure of subjective health in terms of its associations with other factors of health [ 37, 39].
