Provider Perception of Frailty Is Associated with Dialysis Decision Making in Patients with Advanced CKD

Discussion

In this prospective, observational, cohort study of patients with advanced CKD, we found that the prevalence of frailty varied widely depending on the frailty assessment tool used. Furthermore, different frailty and physical function assessment tools did not identify the same individuals as being frail or having poor physical function, as demonstrated by their weak agreement. The subjective measures of frailty (physician and nurse impression ratings) were more strongly associated with treatment decisions (in-center HD versus home dialysis), whereas objective frailty and poor physical function (slowness and weakness from Fried and all components of SPPB) were more strongly associated with all-cause mortality. Together, these findings emphasize that although frailty and poor physical function are common in patients with CKD, the choice of measurement tool used to identify frailty and poor physical function is important in determining diagnostic and prognostic values of this concept in the advanced CKD population.

Previous studies have examined the association of frailty and adverse outcomes in patients with CKD and have concluded that frailty leads to worse outcomes, including death and kidney failure (9,18). These larger studies, on the basis of secondary analyses of data from national health surveys, suggested that frailty is common and associated with adverse clinical outcomes in patients with early-stage CKD. Important limitations to these studies were the inclusion of a relatively low-risk CKD population and the need to modify the Fried criteria in order to accommodate the available data, both of which limited the validity and generalizability of these findings to patients with later stages of CKD referred to and cared for in multidisciplinary CKD clinics.

More recently, investigators from the Seattle Kidney study prospectively evaluated frailty using a slightly modified Fried criteria in >300 patients with CKD followed in nephrology clinics (18). They found that patients with an earlier stage of CKD (mean eGFR of 51 ml/min per 1.73 m²) had a nearly two-fold higher prevalence of frailty compared with an older, community-dwelling, non-CKD reference population. These same investigators then studied another cohort of 385 patients with more advanced CKD (mean eGFR of 41 ml/min per 1.73 m²) and found that gait speed (a criterion in the Fried construct of frailty) was independently associated with mortality in the population, whereas handgrip strength and other biomarkers, such as hemoglobin, albumin, or C-reactive protein, were not (19). However, participants in these studies had relatively preserved kidney function, and investigators did not assess agreement between different methods of measuring frailty or examine the effect of frailty on dialysis treatment modality selection.

To our knowledge, this study is the largest to examine the agreement between subjectively and objectively measured frailty in patients with CKD. Salter et al. (20) recently conducted a cross-sectional analysis examining the agreement between physician-, nurse-, and patient-perceived frailty with objective frailty using the Fried criteria in 146 prevalent patients on HD. Similar to our findings, the investigators reported poor agreement (κ=0.24–0.27) between perceived and objective frailty and concluded that perceived frailty is an inadequate proxy for objective measurement.

Our study suggests that patients who were perceived as frail by nurses and physicians (independent of age, sex, and comorbidity) were less likely to choose or perform home dialysis modalities. These findings are novel because the relationship between frailty and decisions around dialysis commencement and modality has not been previously explored. The decision regarding when and what type of dialysis modality to initiate in a patient with progressive CKD is complex, involving both objective and subjective physician, nurse, and patient/caregiver factors. Although we did not ask patients to classify themselves as frail versus nonfrail, our findings suggest that physicians and nurses may be more likely to recommend in-center HD to patients they perceive are frail versus those diagnosed as frail or having poor physical function using the Fried or SPPB-based criteria, respectively. This discordance is concerning, as provider perception had poor agreement with objective measures of frailty or physical function and was not as strongly associated with a definitive clinical outcome (mortality), whereas the Fried and SPPB criteria were. This important discordance between clinician perception and objectively measured frailty and physical function suggests that clinical gestalt alone may be an inappropriate guide for dialysis modality choice and that subjective and objective definitions of frailty should not be considered interchangeable.

In addition, it is possible that nephrologists and nursing staff encouraged in-center dialysis for more frail patients as part of regular clinical encounters on the basis of their subjective assessment. However, objective measures of frailty have stronger associations with clinical outcomes, and perhaps, advice on treatment decisions, if appropriate, should at least include some objective measures as they are easily implemented by the bedside. In particular, measures of lower-extremity physical function (chair stand test) had strong associations with death and modality selection and can be easily performed at the bedside. Furthermore, our previous study examining technique failure in patients on peritoneal dialysis suggested that these objective criteria were more strongly associated with clinical outcomes when compared with physician/nurse impression (21). Future studies should examine this concept and whether incorporation of objective frailty measures or physical function tests into a dialysis decision support tool for use by patients and physicians leads to better modality decision making and technique survival.

Our findings have important clinical and research implications in this population that is at high risk of progression to kidney failure, cardiovascular events, and death. From a clinical perspective, SPPB is simple, takes minimal time to perform in clinic, and therefore, can be integrated into the bedside. Furthermore, individual components of the Fried (gait speed and grip strength) were independently associated with all-cause mortality, which suggests that an objective frailty assessment needs to be integrated into clinical examination. Whether objective frailty measures improve risk prediction beyond traditional models using clinical and demographic variables, however, remains unknown and needs to be examined further in prospective studies. In addition, our findings on nurse and physician impressions of frailty and its association with the choice of in-center HD need to be validated in independent cohorts.

The strengths of this study include its prospective, multicenter design and the collection of a broad range of clinical, demographic, and laboratory variables in addition to data on frailty and disability. Furthermore, the unique study population of patients with advanced CKD (mean eGFR 20 ml/min) examines a previously unstudied population at exceptionally high risk for kidney failure and all-cause mortality. Finally, the study’s longitudinal design will allow us to continue to prospectively study changes in frailty and physical/cognitive function that occur with dialysis initiation and to assess the effect of these clinical trajectories on clinical outcomes and quality of life.

This study has several limitations. We used a single baseline measurement of frailty and examined the association with downstream adverse events. As frailty status changes, particularly with kidney failure and the initiation of dialysis, the effect of these changes on mortality and dialysis decision making remains unstudied. In addition, most of our mortality outcomes occurred before dialysis, and as such, we are unable to evaluate the effect of dialysis treatment on the frailty trajectory. As we continue follow-up in our study population, we expect that additional outcomes will accrue, and we may be able to examine the association of frailty with postdialysis outcomes. Also, we were unable to collect data on choice of conservative or palliative management of CKD and, therefore, are not able to address the effect this may have had on mortality and dialysis modality choice. We were also not able to attain data on social factors such as caregiver support, education level, and socioeconomic status that may have affected the choice of dialysis modality. We also recognize that a validated SPPB cutoff for patients with CKD has not been established; therefore, a lower cutoff (less than nine) may be more specific for this population. However, we chose the cutoff of ten on the basis of our a priori–defined study protocol. Furthermore, our Canadian study population was mostly of White European descent, so our findings may not be generalizable to other high-risk populations, such as Hispanic and Black populations. Finally, our results may be less applicable to patients with earlier stages of CKD and patients with CKD not followed in nephrology clinics.

In summary, in this prospective cohort study of 603 patients with CKD stages 4 and 5 (eGFR<30 ml/min per 1.73 m²), we have demonstrated that the definition of the frailty construct is important, as there is limited agreement between frailty definitions, and important differences in the relationship of each construct with clinical outcomes. Patients diagnosed as frail using the objective Fried frailty criteria were more likely to die, and patients considered frail by nurses and physicians were more likely to choose in-center HD for KRT. These findings suggest that the methods used to diagnose or define frailty are important in determining its utility for clinical decision making.