INTEROBSERVER VARIABILITY IN THE MEASUREMENT OF DIASTOLIC BLOOD-PRESSURE IN PREGNANCY

Objective: The objective of this study was to evaluate and compare the magnitude of interobserver variability present when measuring Korotko ff phase 4 versus phase 5 in pregnant women. Methods: Three observers with different backgrounds simultaneously measured both phase 4 and ph ase 5 on 98 gravidas. Data were used to estimate detectability rates, perform an analysis of variance to assess interobserver variability, e xamine the distribution of interobserver differences, and evaluate the magnitude of the difference between the two diastolic end points. Mai n Outcome Measures: Detectability rates of phase 4 and phase 5 diastol ic pressure and measures of interobserver variability in diastolic rea dings. Results: Detectability rates were observer dependent, ranging f rom 81% to 96% for phase 4 and from 79% to 85% for phase 5. Analysis o f variance demonstrated similar degrees of interobserver variability f or both end points. Likewise, for any two observers measuring either e nd point, there was a similar number of measurements that differed by at least 8 mm Hg. Lastly, the median difference between the two end po ints was estimated to be 6-12 mm Hg, depending on the observer. Conclu sions: These results do not convincingly favor use of either Korotkoff 4 or Korotkoff 5 in pregnancy. Detectability rates differ among obser vers and interobserver variability in measurement of blood pressure is significant; improved training for all is suggested.