Abstract
INTRODUCTION
A patient with aortic stenosis with an AVA of 1.22 cm2 who stands 5’ 6" and weighs 145 lb has a BSA of 1.76m2 (AV area index = 0.69 cm2/m2). If the same patient weighs 200 lbs, the BSA increases to 2.09 m2 (AV area index 0.58 cm2/m2). Their calculated AV area index therefore changes from the moderate range to the severe range.
PURPOSE
To determine from our ECHO database the effect the current obesity epidemic has on all ECHO variables that are indexed to BSA.
METHODS
Our ECHO database was searched for all patients with the required data variables, gender, age, height (cm)and body weight (kg) were required. Duplicate patients with multiple ECHO studies were removed, only the first ECHO entry being included. Obvious data entry errors were removed (e.g. height 1866 cm, or weight 8.6 kg). Ideal weight was calculated using the Devine formula, ideal weight = Constant + 2.3x[height in inches-60], where constant= 50kg in males and 45.5kg in females. Body surface area in m2 was calculated = [√(height in cm x weight in Kg)/3600]. The paired t-test was used to determine differences between means. A p value of <0.05 was considered significant.
RESULTS
There were 47,761 ECHO studies entered into the database, of which 46,605 (98%) had all the required fields completed. Once duplicates were removed (-15,903) and erroneous data deleted (-158, 0.33%), 30,536 remained. There were 16,160 females aged 58.7 ± 19.2 years, with a mean height of 161.7 ± 7.2cm and 14,376 males aged 59.8 ± 19.2 years, with a mean height of 176.7 ± 7.6 cm. There were statistically significant differences in both men and women between actual and ideal weight and actual and ideal BSA, see Table 1.
CONLUSIONS. For all ECHO measurements where the value is frequently indexed a decision needs to be made to either use the actual BSA or the ideal BSA. It may be more practical to use the ideal BSA which will remain consistent throughout follow up. Using our data any such measurement for females could be multiplied by 1.16 and for males 1.11 (i.e. actual BSA/ideal BSA). It is disappointing to find that, on average, females are 20 kilograms and males 18 kilograms above their ideal weight.
Table 1. Weight females (kg) Weight males (kg) BSA females (m2) BSA males (m2) Number. 16,160 14,376 16,160 14,376 Actual. 73.2 ± 18.9 89.1 ± 19.3 1.80 ± 0.24 2.08 ± 0.24 Ideal. 53.4 ± 6.5 71.4 ± 6.9 1.55 ± 0.13 1.87 ± 0.3 P value. <0.0001 <0.0001 <0.0001 <0.0001 BSA = Body surface area.
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