Conversion of vascular access type among incident hemodialysis patients: description and association with mortality.
BACKGROUND
Limited data exist describing vascular access conversions during the first year on dialysis therapy or the effect of converting to and from a catheter on subsequent mortality risk.


METHODS
Retrospective cohort study.


METHODS
We studied a random sample of incident US hemodialysis patients (initiated long-term dialysis < 30 days before study entry) in the Dialysis Outcomes and Practice Patterns Study (DOPPS; 1996-2004).


METHODS
At dialysis therapy initiation, we assessed vascular access type in use (arteriovenous fistula [AVF], arteriovenous graft [AVG], or catheter) and other patient characteristics. We characterized changes in vascular access type (conversions) by using regularly collected functional status information.


METHODS
We assessed time to all-cause mortality. We first described conversions, then used time-dependent Cox regression to estimate mortality hazard ratios (HRs) for conversions from a catheter to a permanent vascular access (versus no conversion) and conversions from a permanent vascular access to a catheter (versus no conversion).


RESULTS
The study included 4,532 patients; 69.2% were dialyzing with a catheter; 17.6%, with an AVG; and 13.1%, with an AVF. In patients initiating therapy with an AVF or AVG, 22% experienced a conversion (failure), and median times to first failure were 62 and 84 days, respectively. In catheter patients, 59% converted to an AVF/AVG (predominantly AVG [57%]); median times to first conversion were 92 and 66 days, respectively. Conversion to a permanent access was associated with an adjusted mortality HR of 0.69 (95% confidence interval, 0.55 to 0.85). The effect was similar for conversion to an AVF or AVG, and these persisted across demographic groups and facilities with different conversion practices. Conversion from a permanent vascular access to a catheter was associated with an adjusted mortality HR of 1.81 (95% confidence interval, 1.22 to 2.68).


CONCLUSIONS
Potential for residual confounding because of unmeasured factors influencing decision to convert.


CONCLUSIONS
Vascular access conversions are common in incident patients. Continued efforts to increase early nephrologist referral and permanent vascular access placement may help decrease mortality risk in incident dialysis patients.
Bradbury
Brian D
BD
Department of Biostatistics and Epidemiology, Amgen Inc, Thousand Oaks, CA 91320, USA. bradbury@amgen.com
Chen
Fangfei
F
Furniss
Anna
A
Pisoni
Ronald L
RL
Keen
Marcia
M
Mapes
Donna
D
Krishnan
Mahesh
M
D001166:Arteriovenous Shunt, Surgical / Q000009:adverse effects*; D002408:Catheters, Indwelling / Q000009:adverse effects*; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D006435:Renal Dialysis / Q000295:instrumentation*; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013997:Time Factors; D014481:United States / Q000453:epidemiology