Standard laboratory tests to identify older adults at increased risk of death

Abstract

BackgroundOlder adults are at an increased risk of death, but not all people of the same age have the same risk. Many methods identify frail people (that is, those at increased risk) but these often require time-consuming interactions with health care providers. We evaluated whether standard laboratory tests on their own, or added to a clinical frailty index (FI), could improve identification of older adults at increased risk of death.MethodsThis is a secondary analysis of a prospective cohort study, where community dwelling and institutionalized participants in the Canadian Study of Health and Aging who also volunteered for blood collection (n = 1,013) were followed for up to six years. A standard FI (FI-CSHA) was constructed from data obtained during the clinical evaluation and a second, novel FI was constructed from laboratory data plus systolic and diastolic blood pressure measurements (FI-LAB). A combined FI included all items from each index. Predictive validity was tested using Cox proportional hazards analysis and discriminative ability by the area under receiver operating characteristic (ROC) curves.ResultsOf 1,013 participants, 51.3% had died by six years. The mean baseline value of the FI-LAB was 0.27 (standard deviation 0.11; range 0.05 to 0.63), the FI-CSHA was 0.25 (0.11; 0.02 to 0.72), and the combined FI was 0.26 (0.09; 0.06 to 0.59). In an age- and sex-adjusted model, with each increment in the FI-LAB, the hazard ratios increased by 2.8% (95% confidence interval 1.02 to 1.04). The hazard ratios for the FI-CSHA and the combined FI were 1.02 (1.01 to 1.03) and 1.04 (1.03 to 1.05), respectively. The FI-LAB and FI-CSHA remained independently associated with death in the face of the other. The areas under the ROC curves were 0.72 for FI-LAB, 0.73 for FI-CSHA and 0.74 for the combined FI.ConclusionsAn FI based on routine laboratory data can identify older adults at increased risk of death. Additional evaluation of this approach in clinical settings is warranted.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-014-0171-9) contains supplementary material, which is available to authorized users.

The association between frailty, the metabolic syndrome, and mortality over the lifespan

“…This paradox has been seen in other studies of the FI (Howlett et al 2014), and the metabolic syndrome (Maggi et al 2006;Wang et al 2007). Studies suggest that there may be health behavior or indeed biological vulnerability explanations for this morbidity-mortality paradox (Case and Paxson 2005;Kulminski et al 2008b).…”

Sex differences in frailty: A systematic review and meta-analysis

“…Similarly, in the TILDA and Canadian Study of Health and Aging studies, a 0.01 point increase in FI (corresponding to approximately one third of a deficit in each study) was associated with a 3.6% and a 2% increase in risk of two-year and six-year mortality, respectively (Howlett et al, 2014;Theou et al, 2015). Even though…”

“…Recently, studies examining test-based and laboratory-based FIs have revealed new patterns of sex differences (Howlett et al, 2014;Theou et al, 2015). 'Subclinical' deficit accumulation may be where clinical frailty may be low but the risk of adverse outcome is high.…”

Diagnostic Accuracy of Frailty Screening Methods in Advanced Chronic Kidney Disease

“…Published recommendations were used to construct a CKD FI and CKD FI-LAB (online suppl. Table 3, 4, respectively) [22,23,26]. Although the FI was not originally intended to be dichotomised, a cut-off of > 0.21 has been suggested in the literature [26].…”