PMC:4159490 / 6033-15032 JSONTXT

{"project":"2_test","denotations":[{"id":"24777474-3558716-56346669","span":{"begin":146,"end":148},"obj":"3558716"},{"id":"24777474-11157375-56346670","span":{"begin":272,"end":274},"obj":"11157375"},{"id":"24777474-21616714-56346671","span":{"begin":8158,"end":8160},"obj":"21616714"},{"id":"24777474-21616714-56346672","span":{"begin":8826,"end":8828},"obj":"21616714"}],"text":"Measurements\n\nClinical characteristics\nClinical and demographic data including the Charlson Comorbidity Index, using the original scoring system [18], were recorded for each patient; scores for age and severe renal failure were included in the Charlson Comorbidity Index [19]. MHD patients underwent blood and serum measurements, described in Tables 1 and 2, which were performed in the DaVita central laboratory (DeLand, Florida). Blood was obtained immediately before a routine mid-week hemodialysis. Blood test results for MHD patients presented here were values obtained monthly and averaged over the 3 months immediately prior to obtaining the other study measurements. Normal controls had blood drawn for a CBC and serum creatinine and albumin which were measured in the Harbor-UCLA Medical Center clinical laboratory. Normal volunteers who had abnormal test results were excluded from the study. Only one normal was excluded, and that was because the daily physical activity measurements from his ActiGraph (see below) were not available.\nTable 1 Characteristics of study participants\nCharacteristic MHD patients N = 72 Normal controls N = 39 p Value\nAge (years) 52.3 ± 12.9 51.0 ± 12.7 0.570\nGender (M/F) 49/23 23/16 0.391\nMale (%) 68 59\nDM/non-DM 23/49\nDialysis vintage (months) 53.9 ± 45.0\n47.8 (51.4)\nRace (%) 0.423\n African American 29 (40 %) 8 (21 %)\n Asian 22 (31 %) 19 (49 %)\n Caucasian 5 (6.9 %) 4 (10 %)\n Hispanic 15 (21 %) 8 (21 %)\n Pacific Islander 1 (1.4 %) 0\nEducation levels (%) 0.056\n Below high school graduate 14 (19 %) 2 (5.1 %)\n High school graduate 25 (35 %) 14 (36 %)\n ≤2 years of college\n ≥2 years of college 33 (46 %) 23 (59 %)\nCharlson comorbidity index 5.7 ± 2.7 –\nWeight (kg) 78.9 ± 21.5 74.8 ± 14.5 0.237\n76.4 (25.6) 77.0 (18.9)\nBody mass index (kg/m2) 27.8 ± 5.8 27.0 ± 3.9 0.388\n26.2 (7.6) 27.0 (5.9)\nLean body mass (kg) 54.0 ± 15.4 51.4 ± 11.3 0.315\n51.5 (17.7) 49.1 (15.9)\nLean body mass index (kg/m2) 18.9 ± 3.4 18.4 ± 2.7 0.472\n18.3 (3.0) 18.2 (3.2)\nBody fat (%) 28.3 ± 8.5 27.9 ± 8.1 0.786\n26.8 (11) 25.8 (14)\nSerum albumin (g/dL) 4.1 ± 0.3 4.1 ± 0.2 0.606\nSerum creatinine (mg/dL) 10.5 ± 4.3 0.84 ± 0.2 \u003c0.0001\n9.8 (3.8)\nnPNA (g protein/kg/day) 1.10 ± 0.26\nSp Kt/Vurea 1.72 ± 0.40\nSerum TIBC (ug/mL) 240.6 ± 40.1\nSerum ferritin (ng/mL) 453.2 ± 313.2\nHemoglobin (g/dL) 11.2 ± 0.8 13.8 ± 1.3 \u003c0.0001\n11.2 (0.9) 14 (2.1)\nSerum calcium (mg/dL) 9.0 ± 0.7\nSerum phosphorus (mg/dL) 5.3 ± 1.4\nSerum PTH (pg/mL) 480 ± 277\n456 (305)\nSerum bicarbonate (mEq/L) 24.5 ± 2.6\nData expressed as mean ± standard deviation. Non-normally distributed data are expressed as median values with the interquartile range (IQR, i.e., the arithmetic difference between the 25th percentile value and the 75th percentile value) shown in parentheses\nnPNA normalized protein nitrogen appearance, also referred to as protein catabolic rate; TIBC total iron binding capacity; PTH parathyroid hormone\nTable 2 Physical activity and physical performance; MHD patients vs. normal controls\nMHD patients N = 72 Normal controls N = 39 p Value\nHuman activity profile\n Maximum activity score 82.5 (13.5) 92 (5) \u003c0.0001\n Adjusted activity score 72 (22) 89 (5) \u003c0.0001\nTime spent by monitor readings (%)\n Sleep or marked physical inactivity 81.9 ± 5.8 72.8 ± 6.0 \u003c0.0001\n Light activity 14.4 ± 4.4 20.0 ± 4.5 \u003c0.0001\n ≥ Moderate activity 3.7 ± 2.1 7.2 ± 3.0 \u003c0.0001\nAverage daily physical activity (vector magnitude)\n Daily physical activity (mean of 7 days) 395,727 (222,350) 636,112 (243,634) \u003c0.0001\n Day of HD 327,250 (188,085)\n 1-day-post-HD 442,720 (246,824)a\n 2-days-post HD 393,353 (275,123)b\n6-min walk distance (meters) 441.3 ± 121.9 617.6 ± 63.2 \u003c0.0001\nSit-to-stand test (no. cycles in 30 s) 15.9 ± 5.3 26.2 ± 5.4 \u003c0.0001\nStair-climbing test (seconds per 22 stairs) 15.8 ± 11.0 9.8 ± 1.1 \u003c0.0001\nData expressed as mean ± standard deviation. Non-normally distributed data are expressed as median values with the interquartile range (IQR, i.e., the arithmetic difference between the 25th percentile value and the 75th percentile value) shown in parentheses\na1-day-post-HD vs day of HD p = 0.018\nb2-days-post-HD vs day of HD p = 0.057; 1-day-post-HD vs 2-days-post-HD p = 0.441\n\nBody composition studies\nMHD patients and normal subjects visited the HUMC Clinical and Translational Research Center in the morning after fasting for at least eight hours. MHD patients visited the Clinical and Translational Research Center one day after a hemodialysis treatment. Height, body weight, and body mass index (BMI, body weight (kilograms) divided by body height (squared meters)) were measured. No subject had obvious edema at the time of study. Lean body mass, fat mass, and bone mass were measured by dual energy x-ray absorptiometry (Hologic; model DXA Discovery A; Bedford, MA.)\n\nPhysical performance tests\nImmediately after the body composition tests, subjects underwent three physical performance tests in the following order: 6-min walk test (6-MWT), sit-to-stand test, and stair-climbing test. The 6-MWT measured the distance (meters) that participants walked back and forth along an 80-ft (24.4 m) horizontal corridor during a 6-min period of time while they were repetitively encouraged to walk fast. Using a standard 6-MWT protocol, participants were encouraged to walk fast using the following phrases for consistency: “You’re doing well,” “Keep up the good work.” “Good work,” “You have …… minutes to go,” and “You have only …… minutes left.” Study subjects could slow down, rest, or even stop walking if they wished, but the 6-min timer kept running. In the sit-to-stand test, participants rose from a fully seated position to full standing and then returned to the starting fully seated position as frequently as possible, with encouragement, during a 30-s period. This test measured the number of sit-to-stand cycles completed during 30 s. The stair-climbing test measured the time (seconds) for participants to climb 22 steps as fast as possible, again with encouragement, without running, jumping, or skipping steps. The 6-MWT was performed once; the sit-to-stand and stair-climb tests were each performed twice at 5-min intervals, and the better of the two scores was selected for analysis. Participants underwent these physical performance tests after they received a detailed explanation and demonstration of each test by a trained examiner.\n\nDaily physical activity\nDaily physical activity (DPA) was assessed both with a physical activity monitor (ActiGraph GT3X+ Activity Monitor®, ActiGraph, Fort Walton Beach, FL) and a questionnaire, the Human Activity Profile. All participants completed the Human Activity Profile questionnaire, which elicits a person’s description of the frequency that he/she performs physical activities requiring various amounts of energy expenditure and degrees of physical performance [20]. The human activity profile score is calculated as a maximum activity score, indicating the highest oxygen-demanding activity listed in the questionnaire that the subject indicates that he/she still performs. The human activity profile-adjusted activity score is calculated as the subject’s maximum activity score minus the number of less oxygen-demanding physical activities that the subject indicates that he/she can no longer perform. These scores, respectively, estimate the highest level of energy expenditure (the maximum activity score) and average level of energy expenditure (the adjusted activity score) as compared to normal individuals of the same age and gender [20].\nDuring their CTRC visit, study participants were instructed to wear an activity monitor that was strapped to the lateral side of the pelvic bone on the non-dominant side of the hips. The activity monitor (ActiGraph®) was worn continuously for 10 days, including nights, except when subjects took baths, showered, or swam. This pager-sized ambulatory accelerometer detects physical activity in three dimensions. ActiGraph’s digital filtering algorithms measure the frequency and direction of movements by the subject, the orientation of the person’s body (e.g., lying, sitting, standing), and the time of day and date of each movement [21]. Physical activity was calculated during the last seven full days of activity. For MHD patients, these 7 days included three hemodialysis days and four non-hemodialysis days. Thus, on one of these 7 days, daily physical activity was measured on the second day after a hemodialysis.\nThe average daily vector magnitude (VM) for daily physical activity was calculated as the square root of the sum of the squares of the movement readings from each of the three dimensional axes. We classified activity level as sleep or marked physical inactivity (i.e., a VM of 0–500), light physical activity (VM of 501–2689), and moderate or greater physical activity (VM ≥2,690) [21]. A VM score of 0–500 was taken to indicate sleep or marked physical inactivity based upon our observations of the subjects’ activities when these readings were obtained."}