Diabetes Care, Vol 19, Issue 7 764-767, Copyright © 1996 by American Diabetes Association
Rapid HbA1c testing in a community setting
JS Carter, CA Houston, SS Gilliland, GE Perez, CL Owen, DR Pathak and RR Little
Department of Medicine, University of New Mexico School of Medicine, Albuquerque 87131, USA.
OBJECTIVE: To determine whether the DCA 2000 analyzer provides valid and
reliable HbA1c results when used under field conditions and operated by
nonmedical personnel. This study was part of a community diabetes education
program, the Native American Diabetes Project, in which HbA1c was measured
as an indicator of average glycemic control. RESEARCH DESIGN AND METHODS:
Two study samples were taken, the first in the spring of 1994 and the
second in the spring of 1995. Seven community members in 1994 and six new
community members in 1995 were trained over 2 days, using standard
protocol, to operate the DCA 2000 HbA1c analyzer and to collect two
capillary blood samples from participants in the Native American Diabetes
Project. Duplicate DCA 2000 HbA1c measurements performed by the community
workers were compared with measurements from a high-performance liquid
chromatography (HPLC) system. Validity and reliability measures were
calculated. RESULTS: Of the participants, 43 were studied in 1994 and 14 in
1995. Comparison of the mean DCA 2000 results with those of HPLC showed
high validity, with the absolute relative difference between the mean DCA
2000 and the external reference of HPLC (magnitude of mean DCA 2000-HPLC
magnitude of /HPLC) as 4.0 and 2.0% for 1994 and 1995, respectively. The
Pearson correlation coefficients (r) between these two measures were 0.968
and 0.996 for 1994 and 1995, respectively. While the 1994 data appeared to
have less validity for values > 10%, they included only one value with a
60-min warm-up of the DCA analyzer. The 1995 data, all collected after a
60-min warm-up, had good correlation throughout the range of values. The
within-run reliability was excellent, with an intraclass correlation
coefficient of reliability of 0.959 and 0.975 for paired samples, for 1994
and 1995 respectively. The mean coefficient of variation for these paired
measures was 3.0% in 1994 and 2.8% in 1995. Both validity and reliability
were improved by changing the warm-up period of the DCA 2000 analyzer from
5 to 60 min. All correlation coefficients were statistically significant (P
< 0.0001). CONCLUSIONS: The DCA 2000 gave valid and reliable HbA1c
results when operated in a community setting by nonmedical personnel.
Extending the warm-up period of the device to 60 min slightly improved the
validity and reliability of the test.