Supplementary Information
Effects of cold and hot temperature on dehydration: A mechanism of
cardiovascular burden
Authors: Youn-Hee Lim, PhD1,2*, Min-Seon Park, MD3*, Yoonhee Kim, PhD4, Ho Kim, PhD4,5,,
Yun-Chul Hong, MD, PhD1,6§
*These authors contributed equally to this work.
1
Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul,
Korea
2
Environmental Health Center, Seoul National University College of Medicine, Seoul, Korea
3
Department of Family Medicine, Seoul National University Hospital, Seoul, Korea
4
Department of Biostatistics and Epidemiology, School of Public Health, Seoul National
University, Seoul, Korea
5
Institute of Health and Environment, Seoul National University, Seoul, Korea
6
Institute of Medical Research, Seoul National University Bundang Hospital, Seongnam,
Republic of Korea
§
Corresponding author: Y-C Hong, Institute of Environmental Medicine, Seoul National
University Medical Research Center, 103 Daehakro, Jongro-gu, Seoul 110-799, Republic of
Korea. Telephone: +82-2-740-8394; Fax: +82-2-747-4830; E-mail: ychong1@snu.ac.kr
1
Tables of Contents
Supplementary Tables
Supplementary Table S1. Monthly average of four markers (Mean (P-valuea)) ........................................... 3
Supplementary Table S2. Effects of daily mean temperature on dehydration indices per 1°C decrease/ incr
ease at below or above the flexion temperature. ........................................................................................... 7
Supplementary Table S3. Amount of variance (%) explained by apparent temperature (AT): Using individ
ual patients’ dehydration makers................................................................................................................... 8
Supplementary Table S4. Amount of variance (%) explained by apparent temperature (AT): Using daily a
verage of dehydration markers...................................................................................................................... 9
Supplementary Figures
Supplementary Figure S1. Monthly patterns of four markers and apparent temperature (AT)..................... 4
Supplementary Figure S2. Estimated effects per 1°C decrease/increase of mean temperature below /above
temperature flexion points (stratified by hypertension group). .................................................................... 5
Supplementary Figure S3. Plots of changes in dehydration markers according to daily mean temperature c
hange. ............................................................................................................................................................ 6
2
Supplementary Table S1. Monthly average of four markers (Mean (P-valuea))
Plasma Tonicity
BUN/Creatinine
Urine specific gravityb
(mOsm/l)
January
16.11
1022.12
42.55
February
16.30 (0.1079)
1022.18 (0.6765)
42.45 (0.3116)
March
16.33 (0.0514)
1022.15 (0.8351)
42.19 (0.0002)
April
16.28 (0.1404)
1021.45 (<0.0001)
42.13 (<0.0001)
May
16.01 (0.3877)
1020.92 (<0.0001)
42.06 (<0.0001)
June
15.94 (0.1342)
1019.94 (<0.0001)
42.09 (<0.0001)
July
16.23 (0.2725)
1019.75 (<0.0001)
41.69 (<0.0001)
August
15.63 (<0.0001)
1020.17 (<0.0001)
41.69 (<0.0001)
September
15.61 (<0.0001)
1020.18 (<0.0001)
41.82 (<0.0001)
October
15.60 (<0.0001)
1020.80 (<0.0001)
42.07 (<0.0001)
November
16.02 (0.4486)
1020.93 (<0.0001)
42.45 (0.3171)
December
16.27 (0.1610)
1021.51 (<0.0001)
42.24 (0.0009)
a
P-value for Student’s t-test for month difference (Reference: January)
b
Urine specific gravity was multiplied by 1,000.
3
Haematocrit (%)
297.05
296.11 (<0.0001)
296.52 (<0.0001)
297.01 (0.7500)
296.26 (<0.0001)
296.19 (<0.0001)
296.20 (<0.0001)
296.09 (<0.0001)
296.01 (<0.0001)
296.96 (0.4323)
296.81 (0.0402)
296.96 (0.4411)
Supplementary Figure S1. Monthly patterns of four markers and apparent temperature (AT)
BUN/CR: BUN/Creatinine ratio; Usg: Urine specific gravity; Tonicity: Plasma tonicity; HCT: Haematocrit; AT:
apparent temperature
4
Supplementary Figure S2. Estimated effects per 1°C decrease/increase of mean temperature below /above temperature flexion points (stratified by
hypertension group).
Flexion temperature points and lag days were 25.0°C (lag 0–5), 22.8°C (lag 0), and 26.8°C (lag 0–5) for (a) urine specific gravity, (b) plasma tonicity, and (c) haematocrit,
respectively.
5
Supplementary Figure S3. Plots of changes in dehydration markers according to daily mean temperature change.
(A), (B), (C), and (D) are Bun/Creatinine ratio, urine specific gravity, plasma tonicity, and haematocrit, respectively. All models were adjusted for sex, age, body
mass index, alcohol consumption, household income, smoking status, haemoglobin (for haematocrit only), daily mean relative humidity, season, and year.
.
6
Supplementary Table S2. Effects of daily mean temperature on dehydration indices per 1°C decrease/ increase at below or above the flexion
temperature.
Dehydration
Index
Temperature (°C,
Lag days)
Bun/Creatinine ratio
Below flexion
Above flexion
Betaa (SE)
P-value
Betaa (SE)
P-value
22.4 (lag 0-1)
0.036 (0.005)
<0.0001
0.083 (0.021)
0.0001
Urine specific gravityb
24.0 (lag 0-5)
0.073 (0.007)
<0.0001
0.292 (0.041)
<0.0001
Plasma tonicity
22.2 (lag 0)
0.045 (0.005)
<0.0001
0.169 (0.022)
<0.0001
Haematocrit
24.8 (lag 0-5)
0.009 (0.001)
<0.0001
0.038 (0.009)
<0.0001
a
All models were adjusted for sex, age, body mass index, alcohol consumption, household income, smoking status, haemoglobin (for haematocrit only), daily
mean relative humidity, season, and year.
b
Urine specific gravity was multiplied by 1,000.
7
Supplementary Table S3. Amount of variance (%) explained by apparent temperature (AT): Using
individual patients’ dehydration makers
BUN/CR
ratio
Model
All dataa
Cold tails (< flexion point)a
Warm tails (> flexion point)
a
a
Hydration markers
Urine
specific
Plasma
gravity
tonicity
Haematocrit
0.3
2.2
0.3
0.3
0.3
1.9
0.3
0.2
0.6
0.4
0.3
0.1
Generalized linear modeling (GLM) with natural cubic splines of AT in 5 degrees of freedom
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Supplementary Table S4. Amount of variance (%) explained by apparent temperature (AT): Using daily
average of dehydration markers
BUN/CR
ratio
Model
All dataa
Cold tails (< flexion point)a
Warm tails (> flexion point)
a
a
Hydration markers
Urine
specific
Plasma
gravity
tonicity
Haematocrit
1.4
5.8
0.5
1.5
1.4
5.8
0.5
1.5
2.7
3.0
0.7
1.4
Generalized linear modeling (GLM) with natural cubic splines of AT in 5 degrees of freedom.
9