We conducted a single center, randomized, controlled trial among older people who were frail in Sydney, Australia. The trial protocol has been previously reported . The Northern Sydney & Central Coast Health Human Research Ethics Committee has approved the study protocol - Research Protocol Number 0709-191M - and the trial is registered with the Australian New Zealand Clinical Trials Registry: ACTRN12608000250336. Trial registration was delayed and 8% of the participants had been randomized at the time of registration. Participants provided written informed consent before randomization.
Study population, screening and randomization
Eligible participants were identified from older people treated by clinicians working within the Division of Rehabilitation and Aged Care Services (DRACS) at Hornsby Ku-ring-gai Health Service (Sydney, Australia). DRACS is a large clinical service that has programs operating both in the community and hospital settings. Eligible participants first completed their usual treatment program before being approached to enter the study. Following participation agreement, informed consent was sought, often in conjunction with relatives. If granted, the study nurse screened for inclusion criteria. These were: adults aged 70 years or older with three or more of the CHS frailty criteria ; not usually living in a residential aged care facility; residing in the Hornsby or Ku-ring-gai local government areas; without moderate or severe cognitive impairment (defined as a Mini Mental State Examination score of ≤18) ; not an ongoing client of DRACS; without an illness likely to be associated with a life expectancy of <12 months, estimated by a score of ≤3 on a modified version of the Implicit Illness Severity Scale ; and not participating in another physical intervention research project. All randomized participants met the eligibility criteria.
Participants in the intervention group received a multifactorial, interdisciplinary treatment program intended to target frailty for a 12-month period following randomization. The interventions were individually tailored to each participant based on their frailty characteristics as assessed at baseline, and additional problems as identified during a detailed assessment by the two experienced physiotherapists providing the intervention program. Geriatric evaluation and management principles underpinned both the assessment and intervention .
Details of the approach to intervention are described in the protocol paper . To summarize, the CHS frailty components that were present in each participant were specifically targeted . If the participant met the weight loss criterion, a dietician evaluated nutritional intake. Home-delivered meals were recommended if appropriate clinical criteria applied. In addition, if the participant's body mass index was <18.5 kg/m2, or mid-upper arm circumference was <the 10th percentile (using Australian age and gender specific norms), nutritional supplementation was offered using commercially available, high energy, high protein supplements.
If the exhaustion criterion was met and the Geriatric Depression Scale  score was high, the study team considered referral to a psychiatrist or psychologist. Where the participant was socially isolated, options to encourage greater social engagement were identified, such as participation in day activity groups and telephone contact with a volunteer.
Participants who met the weakness, slowness or low energy expenditure criteria received up to 10 home-based physiotherapy sessions and performed a home exercise program, over the course of 12 months. The Weight-bearing for Better Balance (WEBB) program , designed to improve mobility, increase physical activity and prevent falls, was tailored to individual's physical impairments, prescribed three to five times per week, and reviewed regularly. Two physiotherapy sessions targeted the participant's mobility goal. Equipment was also recommended as necessary.
Case management by the physiotherapist, and regular case conferences involving the physiotherapist, geriatrician, rehabilitation physician, nurse and dietician, facilitated coordination of the delivery of the intervention. Reassessment was ongoing throughout the intervention phase. The physiotherapist was the co-ordinator of the intervention. Home visits usually involved several intervention components and included not only the WEBB exercise program, but other identified interventions that were relevant to the frail person at that particular time.
For all participants, additional interventions were then provided or recommended based on a comprehensive geriatric evaluation, for example review by the study geriatrician or rehabilitation physician, follow-up of chronic diseases, treatment of pain, and management of other identified conditions such as urinary incontinence.
The major limiting factor in implementing the intervention as planned was the limited ability of the participants to be able to adhere with the recommended intervention plan. The physiotherapists coordinating the intervention were careful not to overwhelm the participants with complex treatment plans and, in addition, participants often declined specific interventions.
There was a standardized approach to interventions in the study based on the study protocol and regular case discussions of each participant. The physiotherapist primarily responsible for each participant documented adherence to the study protocol and estimated a global level of adherence (in five categories) over the 12-month intervention period.
Usual care, as received by the control group in this study, consisted of those health and aged care services that would normally be available to older people. These include general practitioner and medical specialist consultations, and nursing and allied health interventions as appropriate. Australia has a system of universal health insurance so that all of its population has access to health care without significant cost. Aged care services include assistance with housekeeping and personal care and these types of services are also heavily subsidized by the Australian government for older people with care needs. Northern Sydney has a well-developed system of health and aged care that has been operating in its current form for more than 20 years.
The primary outcomes measured were frailty and mobility. Frailty was assessed using the CHS definition of the frailty syndrome . See Additional file 1 for details of frailty assessment criteria. Mobility was measured using the SPPB , which assesses the ability to stand (for 10 s) with the feet together in the side-by-side, semi-tandem and tandem positions; time to walk 4 meters; and time to rise from a chair and return to the seated position five times. The SPPB score and the lower extremity continuous summary performance score were calculated .
Secondary outcomes included hospitalizations and admissions to nursing care facilities that were reported on monthly calendars and confirmed from either hospital records or the relevant facility; disability was measured with the Barthel Index , and health-related quality of life measured by the EuroQol-5D (EQ-5D) . Psychological status was assessed using the Geriatric Depression Scale (short form)  and deaths were recorded and verified by hospital records.
We initially chose the Timed Up and Go measure as a co-primary outcome and included this on the Clinical Trials Registry. However, early in the study we recognized that it was not feasible to collect data for this outcome and hence determined that the SPPB and Frailty would be the co-primary outcome measures. These are the co-primary outcomes recorded in the study protocol paper .
The data were collected in the participants' homes by experienced research nurses trained specifically for the trial. Training in the assessment tools was provided, and joint sessions conducted to standardize the administration of the assessment tools, ensuring consistent interpretation of the data recorded. Inter-rater reliability checks were conducted at commencement and mid-way through the trial.
The study aimed to recruit approximately 230 participants, to detect a clinically and statistically significant 15% difference in mobility as assessed by the lower extremity continuous summary performance score between the two groups (power = 80%, P = 0.05, dropouts = 15%, non-compliance = 15%, standard deviation (SD) = 0.7).
A permuted block randomization approach was used to achieve balanced treatment allocation. There were two strata (frail with three CHS frailty criteria and very frail with four or five CHS frailty criteria). A random number sequence was generated for the order of treatment allocation within the blocks using SPSS v15 RV.UNIFORM function (SPSS, Inc., Chicago, IL, USA). Block sizes of four and six were used and these blocks were randomly arranged within blocks of ten.
Project personnel not involved in assessing participants or in providing the intervention managed the randomized group allocation. The treatment allocation tables for both strata were stored centrally off site.
Staff members performing the outcome assessment and data analysis were masked to group allocation. It was not possible to blind participants and staff administering the interventions to group allocation. The number of participants inadvertently unblinding the outcome assessors was recorded.
Adverse events were monitored and recorded by the treating clinicians. Deaths were monitored by the study statistician. A data monitoring procedure was implemented but, after consultation with the independent epidemiologist monitoring the study, interim analyses were not performed because of the limited number of adverse events.
The study design assessed study participants at baseline, at 3 months, and at 12 months after randomization. Data were coded to permit blinding to group allocation in the statistical analysis. The primary analyses were undertaken in accordance with the intention-to-treat principle. Frailty was treated as both a dichotomous (that is, more than three CHS criteria met or not) and continuous variable, and other study outcomes as continuous variables. The chi-square test was used for frailty as a dichotomous variable, and linear regression models with baseline values as a covariate were used for continuous outcomes. We report between-group differences in percentages, or mean, with 95% confidence intervals (CIs) at the 3- and 12-month follow-ups. We tested whether the pattern of changes in frailty and mobility were modified by frailty severity at baseline, by including an interaction term of study groups with frailty severity at baseline in the regression analyses. Secondary analyses were also carried out to explore the effect of different rates of adherence (as a category variable: <25%, 25% to 49%, 50% to 74% and ≥75%) on the outcomes in the intervention group at the 12-month follow-up. The Cox regression model was used to assess time to admission for those permanently admitted to aged care facilities.