The sensitivity and specificity of the Goldberg cut-off for EI : BMR for identifying diet reports of poor validity

Objective: To explore the specificity and sensitivity of the Goldberg cut-o ff for EI:BMR for identifying diet reports of poor validity as compared wit h the direct comparison of energy intake with energy expenditure measured b y doubly-labelled water. Design: Twenty-two studies with measurements of total energy expenditure by doubly-labelled water (EE), basal metabolic rate (BMR) and energy intake ( EI) provided the database (n = 429). The ratio EI:EE provided the baseline definition of under- (UR), acceptable- (AR) and over-reporters (OR), respec tively EI:EE < 0.76, 0.76-1.24 and > 1.24. Four strategies for identifying under- and over-reporters using the Goldberg cut-off were explored. Sensiti vity of the cut-off was calculated as the proportion of UR correctly identi fied and specificity as the proportion df non-UR correctly identified. Results: UR, AR and OR (by EI:EE) were 34, 62 and 4% respectively of all su bjects. When a single Goldberg cut-off for the physical activity level (PAL ) of 1.55 was used, for men and women respectively the sensitivity was 0.50 and 0.52 and the specificity 1.00 and 0.99. Using a cut-off for higher PAL traded specificity for sensitivity. Using the cut-off for a PAL of 1.95, s ensitivity was 0.76 and 0.85 and the specificity 0.87 and 0.78 for men and women respectively. Using cut-offs for mean age-sex specific PAL did not im prove sensitivity. When subjects were assigned to low, medium and high acti vity levels and cut-offs for three different PALs used, sensitivity improve d to 0.74 and 0.67 without loss of specificity (0.97 and 0.98), for men and women respectively. If activity levels for men were applied to the womens' data, sensitivity improved to 0.72. Conclusion: To identify diet reports of poor validity using the Goldberg cu t-off for EI:BMR, information is needed on each subject's activity level.