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the cohort studied represents a convenience sample of emergency - department patients with triage capillary blood glucose 250 mg / dl enrolled on 320 individual days over a 2-year period based on research - assistant availability .
subjects were excluded if they were 1 ) critically ill , 2 ) in police custody , 3 ) suffering from acute psychosis , or 4 ) unable to give informed consent .
included patients had a urine dipstick ( siemens multistix 10sg ) for ketones ( recorded as positive or negative ) , a serum chemistry panel , a venous blood gas to determine serum ph , and a point - of - care capillary -ohb measurement ( precision xtra meter ; medisense / abbott laboratories ) .
dka was defined according to the following ada criteria : serum glucose 250 mg / dl ; anion gap > 10 mmol / l ; carbon dioxide 18 mmol / l ; and ph 7.30 ( 7 ) .
subjects race , ethnicity , age , sex , previous history of diabetes , and insulin use were recorded .
on the basis of previous literature , we assumed that the true sensitivity of -ohb for detecting dka was between 98 and 100% and determined that a sample including 54 cases of dka would confirm this point estimate with a confidence limit no lower than 90% ( 812 ) .
data were analyzed using stata version 10.0 ( statacorp , college station , tx ) .
diagnostic test characteristics with 95% cis were calculated . according to the manufacturer s guidelines , point - of - care -ohb 1.5 mmol / l was considered negative and > 1.5
mmol / l was considered positive . the difference in specificity for -ohb and urine dipstick ketones
we explored the optimal capillary -ohb cutoff by creating a receiver - operator curve and analyzing diagnostic test characteristics at various cutoffs .
the cohort studied represents a convenience sample of emergency - department patients with triage capillary blood glucose 250 mg / dl enrolled on 320 individual days over a 2-year period based on research - assistant availability .
subjects were excluded if they were 1 ) critically ill , 2 ) in police custody , 3 ) suffering from acute psychosis , or 4 ) unable to give informed consent .
included patients had a urine dipstick ( siemens multistix 10sg ) for ketones ( recorded as positive or negative ) , a serum chemistry panel , a venous blood gas to determine serum ph , and a point - of - care capillary -ohb measurement ( precision xtra meter ; medisense / abbott laboratories ) .
dka was defined according to the following ada criteria : serum glucose 250 mg / dl ; anion gap > 10 mmol / l ; carbon dioxide 18 mmol / l ; and ph 7.30 ( 7 ) .
subjects race , ethnicity , age , sex , previous history of diabetes , and insulin use were recorded .
on the basis of previous literature , we assumed that the true sensitivity of -ohb for detecting dka was between 98 and 100% and determined that a sample including 54 cases of dka would confirm this point estimate with a confidence limit no lower than 90% ( 812 ) .
data were analyzed using stata version 10.0 ( statacorp , college station , tx ) .
diagnostic test characteristics with 95% cis were calculated . according to the manufacturer s guidelines , point - of - care -ohb 1.5
mmol / l was considered negative and > 1.5 mmol / l was considered positive . the difference in specificity for -ohb and urine dipstick ketones was assessed using the mcnemar test with a yates correction ( 13 ) .
we explored the optimal capillary -ohb cutoff by creating a receiver - operator curve and analyzing diagnostic test characteristics at various cutoffs .
a total of 859 patients were screened , 616 provided informed consent , and 516 ( 83.7% ) had all data elements necessary for data analysis ( excluded patients : 49 with no urine dipstick , 30 with no serum ph via venous blood gas , and 21 with no serum chemistry panel ) . in our final sample ,
54 of 516 subjects ( 10.5% ) met the ada criteria for dka . see table 1 for sample characteristics .
demographic and laboratory characteristics of the study sample data are median ( interquartile range ) , unless otherwise indicated . at the manufacturer - suggested cutoff of > 1.5 mmol / l ,
the sensitivity of capillary -ohb and the urine dipstick for dka were identical at 98.1% ( 95% ci 90.1100 ) .
however , the specificity of -ohb was significantly higher than that of the urine dipstick ( 78.6 [ 74.582.2 ] vs. 35.1% [ 30.739.6 ] ; p < 0.01 ) .
positive and negative predictive values of capillary -ohb were 34.9 ( 27.343 ) and 99.7% ( 98.5100 ) , respectively .
positive and negative predictive values of the urine dipstick were 15 ( 11.519.2 ) and 99.4% ( 96.6100 ) , respectively .
test characteristics of -ohb were stable across a wide range of potential cutoffs ( table 1 ) .
mmol / l , where sensitivity remains at 98.1% but specificity improves to 82.3% ( supplementary data ) .
a total of 859 patients were screened , 616 provided informed consent , and 516 ( 83.7% ) had all data elements necessary for data analysis ( excluded patients : 49 with no urine dipstick , 30 with no serum ph via venous blood gas , and 21 with no serum chemistry panel ) . in our final sample ,
54 of 516 subjects ( 10.5% ) met the ada criteria for dka . see table 1 for sample characteristics .
demographic and laboratory characteristics of the study sample data are median ( interquartile range ) , unless otherwise indicated .
at the manufacturer - suggested cutoff of > 1.5 mmol / l , the sensitivity of capillary -ohb and the urine dipstick for dka were identical at 98.1% ( 95% ci 90.1100 ) .
however , the specificity of -ohb was significantly higher than that of the urine dipstick ( 78.6 [ 74.582.2 ] vs. 35.1% [ 30.739.6 ] ; p < 0.01 ) . positive and negative predictive values of capillary -ohb were 34.9 ( 27.343 ) and 99.7% ( 98.5100 ) , respectively .
positive and negative predictive values of the urine dipstick were 15 ( 11.519.2 ) and 99.4% ( 96.6100 ) , respectively .
test characteristics of -ohb were stable across a wide range of potential cutoffs ( table 1 ) .
mmol / l , where sensitivity remains at 98.1% but specificity improves to 82.3% ( supplementary data ) .
approximately one - fourth of emergency - department patients have diabetes , and almost half have poor glycemic control ( 2 ) .
common clinical emergency - department practice is to consider the diagnosis of dka in all patients presenting with blood glucose 250 mg / dl regardless of the reason for the visit . because emergency - department overcrowding has stretched resources to the breaking point , there is increasing emphasis on developing , testing , and using the most rapid , accurate , and easy - to - use dka screening tool available .
the results of this study show that the specificity of capillary point - of - care -ohb is superior to the urine dipstick .
two retrospective emergency - department studies have shown that capillary point - of - care -ohb is 100% sensitive for dka ( 8,9 ) .
( 10 ) likewise found that -ohb was 100% sensitive in a prospective study of seven dka patients .
( 11 ) reported a -ohb sensitivity for dka of 98% in a prospective sample of 160 patients ( 57 with dka ) .
our study is the first to prospectively compare the test characteristics of point - of - care -ohb against the urine dipstick in a cohort of emergency - department patients . using -ohb in lieu of the urine dipstick to screen our sample
first , we did not provide specific training to the nurses who interpreted the urine dipsticks .
we felt this was unnecessary because they 1 ) are clinical laboratory improvement amendment certified , 2 ) are familiar and comfortable with this process , and 3 ) do so regularly in routine clinical practice .
second , the urine dipstick was considered only negative or positive , and consideration of trace / small ketones versus moderate / large ketones may impact the findings .
third , we did not send blood samples to the laboratory for an enzymatic analysis to correlate the values measured by the point - of - care -ohb meter because , despite early concerns , current - generation -ohb meters have been shown to be highly accurate compared with laboratory enzymatic analysis ( 6,14 ) .
fourth , although there are many ways to define dka , we chose to use the ada definition because this is commonly used in dka literature , allowing for direct comparison between our results and previous reports . in conclusion ,
point - of - care capillary -ohb testing at a cutoff of > 1.5 mmol / l was equally sensitive ( 98.1% ) but markedly more specific ( 78.6 vs. 35.1% ) than the urine dipstick for the detection of dka in our prospective sample of emergency - department patients with hyperglycemia . utilizing point - of - care -ohb testing has the potential to substantially reduce comprehensive laboratory evaluations for dka among hyperglycemic emergency - department patients .
objectivein the emergency department , hyperglycemic patients are screened for diabetic ketoacidosis ( dka ) via a urine dipstick . in this prospective study , we compared the test characteristics of point - of - care -hydroxybutyrate ( -ohb ) analysis with the urine dipstick.research design and methodsemergency - department patients with blood glucose 250 mg / dl had urine dipstick , chemistry panel , venous blood gas , and capillary -ohb measurements . 
 dka was diagnosed according to american diabetes association criteria.resultsof 516 hyperglycemic subjects , 54 had dka . 
 the urine dipstick had a sensitivity of 98.1% ( 95% ci 90.1100 ) , a specificity of 35.1% ( 30.739.6 ) , a positive predictive value of 15% ( 11.519.2 ) , and a negative predictive value of 99.4% ( 96.6100 ) for dka . using the manufacturer - suggested cutoff of > 1.5 mmol / l , -ohb had a sensitivity of 98.1% ( 90.1100 ) , a specificity of 78.6% ( 74.582.2 ) , a positive predictive value of 34.9% ( 27.343 ) , and a negative predictive value of 99.7% ( 98.5100 ) for dka.conclusionspoint-of-care -ohb and the urine dipstick are equally sensitive for detecting dka ( 98.1% ) . 
 however , -ohb is more specific ( 78.6 vs. 35.1% ) , offering the potential to significantly reduce unnecessary dka work - ups among hyperglycemic patients in the emergency department .