The most prevalent and expensive public health condition in the United States, affecting 100 million people in the country, with an annual cost to society of $635 billion, is chronic pain (Gereau et al., 2014).  The costs associated with chronic pain are greater than the yearly costs of AIDS, heart disease, and diabetes combined.  Even though chronic pain affects individuals of all races, ages and genders, members of certain population groups are disproportionately affected, particularly seen as being more prevalent and disabling in older adults. However, since chronic pain is often seen as a symptom of underlying disease versus a disease on its own, which now we know it is, its measurement and negative impact on daily life is often overlooked in this population. The proposed research seeks to understand how self-reported measures of physical function and disability relate to performance-based measures that are more objective to assess pain’s impact on function and daily living.

The purpose of the proposed USP work is to compare a validated self-reported measure of physical function and disability in older individuals with a standardized performance-based measure of physical function in older individuals with and without high impact chronic pain. Further, we will test associations of both physical function measures with self-reported and experimental measures of pain using questionnaires and quantitative sensory testing. Because of the limitations during the pandemic, we will employ data collected from the NIH-funded Neuromodulatory Examination of Pain and Function Across the Lifespan (NEPAL) study (IRB 201401056). The study uses three age groups: older adults with chronic pain (60 years old and older), older adults with no pain (60 years old and older), and young controls (18 to 25 years old) to study the inter-individual differences and age-related differences in pain modulation. However, the proposed research question will only focus on the older adults. Participants are screened for a number of diseases to be considered eligible. These measures exclude any participants who experience depression, dementia, have multiple sclerosis, have uncontrolled high blood pressure, currently have cancer or any foreign tumor in the body, liver or kidney disease, bipolar disorder, schizophrenia, Parkinson’s and Alzheimer’s disease. If eligible, the participants complete a number of laboratory visits collecting a battery of questionnaires, cognitive and physical tests to assess their pain, cognition and mobility. The specific test that will be used for the proposed research question is the PAT-D questionnaire and the Short-Form Physical Performance Battery (SPPB). All questionnaires and physical battery performed were standardized across all participants. The Pepper Assessment Tool for Disability (PAT-D) has been used to assess physical function and subjective disability in older adults asking questions surrounding an individual’s basic activities of daily living (ADLs) and instrumental activities of daily living (IADLs), which consist of daily functions and tasks to care for one’s own needs, such as person hygiene, dressing, and eating as well as mobility.  The Short-Form Physical Performance Battery (SPPB) measures mobility and balance tests, repeated chair-stand test and the pain experienced during performance of these tasks. The QST battery measures collected include thermal and mechanical detection, as well as thermal and mechanical pain thresholds on the left thenar eminence and the second metatarsal digit for all individuals in our sample.  We will use principal component and exploratory factor analysis to compare measures as well as linear regressions to assess associations while accounting for important confounders of these associations.

Gereau, R. W., Sluka, K. A., Maixner, W., Savage, S. R., Price, T. J., Murinson, B. B., Sullivan, M. D., … Fillingim, R. B. (2014). A pain research agenda for the 21st century. The journal of pain: official journal of the American Pain Society, 15(12), 1203-14.