Age and Ageing journal 50th anniversary commentary seriesWhy illness is more important than disease in old age.

Clinical reasoning and research in modern geriatrics often prioritises the disease concept. This is understandable as it has brought impressive advances in medicine (e.g. antibiotics, vaccines, successful cancer treatment and many effective surgeries). However, so far the disease framework has not succeeded in getting us to root causes of many age-related chronic diseases (e.g. Alzheimer's disease, diabetes, osteoarthritis). Moreover, in aging and disease constructs alone fail to explain the variability in illness presentations. Therefore, we propose to apply the underused illness concept in a new way by reconsidering the importance of common symptoms in the form of a dynamic network of symptoms as a complementary framework. We show that concepts and methods of complex system thinking now enable to fruitfully monitor and analyse the multiple interactions between symptoms in such in networks, offering new routes for prognosis and treatment. Moreover, close attention to the symptoms that bother older persons may also improve weighing the therapeutic objectives of well-being and survival and aligning treatment targets with the patients' priorities.

Improvements in physical function and pain sustained for up to 10 years after knee or hip arthroplasty irrespective of mental health status before surgery.

Background and purpose - There are concerns that mental health (MH) may influence outcomes of total knee arthroplasty (TKA) or total hip arthroplasty (THA). We examined effects of poor MH before surgery on long-term outcomes of osteoarthritis-related TKA or THA in women. Patients and methods - The data were from 9,737 middle-aged participants (47-52 years) and 9,292 older participants (73-78 years) in the Australian Longitudinal Study on Women's Health who completed surveys between 1998 and 2013. Dates of arthroplasties were obtained from the Australian Orthopaedics Association National Joint Replacement Registry. Participants without procedures were matched with participants with procedures. Trajectories of the Short-Form 36 scores for physical functioning, bodily pain, social functioning, and mental health based on mixed modeling were plotted for participants with and without surgery (stratified according to mental health, separately for TKA and THA, and for middle-aged and older participants). Results - In middle-aged women with poor and good MH, TKA improved physical function and reduced bodily pain, with improvements sustained up to 10 years after surgery. TKA contributed to restoration of social function in women with good MH, but this was less clear in women with poor MH. In both MH groups, mental health appeared to be unaffected by TKA. Similar patterns were observed after THA, and in older women. Interpretation - Recovery of physical and social function and reductions in pain were sustained for up to 10 years after surgery. Improvements in physical function and pain were also observed in women with poor mental health. Thus, in our view poor mental health should not be a contraindication for arthroplasty.

Validity of self-report methods for measuring sedentary behaviour in older adults.

OBJECTIVE: Sedentary behaviour (SB) is associated with a range of negative health outcomes, but little is known about the validity of self-report methods for measuring SB in older adults. Thus, the aim was to assess the reliability and validity of two instruments for measuring SB in older adults. DESIGN: Cross-sectional study. METHODS: 41 community-dwelling older adults (14/27 male/female, 74.5 ± 7.6 years) wore an ActivPAL(3)™ (AP) for 7 consecutive days, then completed (1) a single question (SQ) to assess sitting time on a usual weekday, weekend day and yesterday (i.e. the last day of monitoring), and (2) a computer-delivered 24-h recall (MARCA) for the last two days. Intraclass correlation (ICC) and standard error of measurement (SEM) were used to assess test-retest reliability; validity was examined using Spearman's correlation, mean bias and limits of agreement, and kappa for classifying tertiles of time in SB, with AP as the reference standard. RESULTS: For the SQ, the ICC ranged from 0.64 to 0.79, with SEM 1.03-1.42 h/day. ICC for the MARCA ranged from 0.72 to 0.96, with SEM 0.47-1.18 h/day. The SQ showed modest correlation with AP (r = 0.13-0.33), with mean biases of about -3.5 h/day. The MARCA showed moderate correlation with AP (r = 0.49-0.67), with mean biases of about 1.4 h/day. When categorised into tertiles, agreement was significant but fair for the SQ, and moderate for the MARCA. CONCLUSION: Both measures have acceptable reliability, but the MARCA provides more valid estimates of SB than the SQ, which underestimates SB in this group of older adults.