Predictive value of a profile of routine blood measurements on mortality in older persons in the general population: the Leiden 85-plus Study

Abstract

Background: Various questionnaires and performance tests predict mortality in older people. However, most are heterogeneous, laborious and a validated consensus index is not available yet. Since most older people are regularly monitored by laboratory tests, we compared the predictive value of a profile of seven routine laboratory measurements on mortality in older persons in the general population with other predictors of mortality; gait speed and disability in instrumental activities of daily living (IADL).

Methodology/principal findings: Within the Leiden 85-plus Study, a prospective population-based study, we followed 562 participants aged 85 years for mortality over five years. At baseline (age 85 years) high-density lipoprotein cholesterol, albumin, alanine transaminase, hemoglobin, creatinin clearance, C-reactive protein and homocysteine were measured. Participants were stratified based on their number of laboratory abnormalities (0, 1, 2-4 and 5-7). The predictive capacity was compared with gait speed (6-meter walking test) and disability in IADL (Groningen Activity Restriction Scale) by C-statistics. At baseline, 418 (74%) 85-year old participants had at least one laboratory abnormality. All cause mortality risk increased with increasing number of laboratory abnormalities to a hazard ratio of 5.64 [95% CI 3.49-9.12] for those with 5-7 laboratory abnormalities (p<0.001) compared to those without abnormalities. The c-statistic was 0.66 [95% CI 0.59-0.69], similar to that of gait speed and disability in IADL.

Conclusions/significance: In the general population of oldest old, the number of abnormalities in seven routine laboratory measurements predicts five-year mortality as accurately as gait speed and IADL disability.

Figure 1. Kaplan Meier cumulative mortality curves for all cause mortality according to the three models.

(A) laboratory profile based on sex specific quartiles of the seven included laboratory values, (B) sex specific quartiles of gait speed and (C) sex specific quartiles of instrumental activities of daily living (IADL) at age 85 years. A - - - no laboratory abnormalities n = 144, -----1 laboratory abnormality n = 165, -----2–4 laboratory abnormalities n = 216, -----5–7 laboratory abnormalities n = 37. B - - - 6-meter gait speed male 0.69 –1.37 m/s; female 0.89–1.61 m/s n = 139, ----- 6-meter gait speed male 1.38–1.81 m/s; female 1.61–2.15 m/s n = 142, ----- 6-meter gait speed male 1.81–2.81 m/s; female 2.16–3.95 n = 141, -----6-meter gait speed male 2.91–13.0 m/s; female 4.00–13.00 m/s n = 140. C - - - IADL-score male 9–11; female 9–12 n = 136, ----- IADL-score male 12–16; female 13–18 n = 141, ----- IADL-score male 17–24; female 19–28 n = 145, ----- IADL-score male 25–36; female 29–36 n = 139.

Figure 2. Performance of the three models for 5-year all-cause mortality in 562 participants aged 85 years.

The three models were based on the profile of laboratory abnormalities, sex-dependent quartiles of gait speed and sex-dependent quartiles of the IADL-disability score. ----- Laboratory profile - - - Gait speed . . . IADL-disability score.