Association between time of referral and survival in the first year of dialysis in diabetics and the elderly

Abstract

Objective: The objective of the study was to estimate the association between time of referral and survival during dialysis in diabetics and patients aged≥70 years.

Design, setting and subjects: This study was a prospective follow-up study in 1438 incident dialysis patients (1996-2004, 62% male, 60±15 years) in The Netherlands. Main outcome measures. Referral (time between first pre-dialysis visit to a nephrologist and dialysis initiation) was classified as: late (<3 months), early (3-12 months) or very early (≥12 months). All-cause mortality risk within the first year of dialysis was calculated [HR (95% confidence interval, CI), adjusted for age, sex and primary kidney disease (PKD)]. Additive interaction between time of referral and diabetes mellitus (adjusted for age and sex) or age (adjusted for sex and PKD) was assessed by synergy index [S (95% CI)].

Results: Thirty-two percent were late referred, 12% early and 56% very early; 21% had diabetes; and 30% were ≥70 years. Early and late referrals were associated with increased mortality compared with very early referral [HRadjearly: 1.5 (1.0, 2.4), late: 1.8 (1.3, 2.5)]. A similar trend was observed in diabetics and non-diabetics. However, no interaction between time of referral and diabetes was present [Slate 0.8 (0.4, 1.9), Searly 1.2 (0.4, 3.6)]. Likewise, in patients aged<70 and ≥70 years, time of referral was associated with increased mortality, without interaction [Slate 0.9 (0.4, 1.8), Searly 0.8 (0.3, 2.0)].

Conclusion: Late referral is associated with increased mortality in the first year of dialysis. Diabetes or high age does not have an additional worsening effect, implying that timely referral is important in future dialysis patients irrespective of diabetes or high age.