Fourth, any attempt to equate "functional difficulty" of an ongoing task is likely to have limited ecological validity and real-life relevance.
Einstein and McDaniel [11] explained that they made their ongoing task easier for older vs. younger adults because "this [making word lists shorter for older vs. younger adults] equated functional difficulty" of the ongoing task.
One might argue that Einstein and McDaniel [4] and others who incorporated the ease of ongoing task confound into their designs aimed to equate functional difficulty of ongoing tasks for younger and older adults and that age declines under these "functionally equated" conditions reflect true age differences in prospective memory.
Such information could either be obtained by further analysis of functional difficulties with other measures of participation such as health, employment and education status among people with and without disability from censuses [ 5].
Maxillary constriction can be associated with several problems that include occlusal disharmony and esthetics as well as such functional difficulties as narrowing of the pharyngeal airway, increased nasal resistance, and alterations in tongue posture, resulting in retroglossal airway narrowing and mouth breathing [3 5].
For example, the significant differences in characteristics of the excluded participants (due to missing data, see Statistical Analysis section above) suggest a possible bias as the oldest-old, males, and those with increased functional difficulties and number of medications were less likely to be included in the final sample.
The strength of the study lies in the representation of functional difficulties and ill-health in an entire population of elderly rural villagers and in the completeness of the data: there were very few refusals and the paramedics were scrupulous about completing every question.
Multi-faceted approaches comprising an interdisciplinary healthcare team has proven more efficacious in encouraging behavioural change than a single approach in addressing functional difficulties [ 4], risk of falls [ 12], number of people who fall and fall rates [ 13, 14] and poor nutrition status [ 15]; whether home-based [ 16, 17] or in a community setting [ 18].
For example, the highest item response category on the functional difficulty scale of the OA-FUNCTION-CAT was slightly over 80, whereas the WOMAC was limited to a little over 70 as its highest item response category expected score.
The PHQ-9 is a 10-item self-report depression scale which scores each of the nine Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for a diagnosis of major depression episode plus an extra item on functional difficulties as a result of the depressive symptoms.
