Given the task definition and input, reply with output. Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

This study aims to evaluate the potential effects of renal function variations on vascular structure before the development of hypertension.', 'This pilot study included 141 postmenopausal women without evidence of renal dysfunction or hypertension. Markers of renal function and levels of glomerular filtration rate (GFR)--using standard calculations (GFR based on levels of creatinine [GFR(epi)]) and newer creatinine and/or cystatin calculations (GFR based on levels of creatinine and cystatin [GFR(cr cystatin)] and GFR based on levels of cystatin [GFR(cystatin)])--were associated with hemodynamic parameters and markers of vascular structure (intima-media thickness [IMT] and presence of atheromatous plaques in carotid and femoral arteries).', 'Levels of GFR(epi), GFR(cr cystatin), and GFR(cystatin) exhibited a significant negative correlation with femoral artery IMT, whereas levels of GFR(epi) correlated significantly with mean carotid bulb (CB) IMT. Multivariate analysis showed that CB-IMT was predicted by GFR(epi) levels and age (-coefficient = -0.212, P = 0.020), whereas femoral artery IMT was predicted by GFR(epi) levels (-coefficient = -0.293, P = 0.001). GFR(epi) levels lower than the 25th percentile were associated with higher CB-IMT (P = 0.009), femoral artery IMT (P = 0.001), and combined IMT (P = 0.035) compared with higher GFR(epi) levels. Moreover, GFR(epi) levels greater than the 25th percentile were associated with lower odds for the presence of atherosclerotic plaques at the CB and carotid arteries combined (CB: odds ratio, 0.146; P = 0.006; combined: odds ratio, 0.249; P = 0.043) compared with lower GFR(epi) levels.
Are variations in glomerular filtration rate associated with subclinical atherosclerosis in healthy postmenopausal women?