title: Pattern and determinants of hospitalization during heat waves: an ecologic study.
abstract: BACKGROUND
  Numerous studies have investigated mortality during a heatwave, while few have quantified heat associated morbidity. Our aim was to investigate the relationship between hospital admissions and intensity, duration and timing of heatwave across the summer months.
  
  
  METHODS
  The study area (Veneto Region, Italy) holds 4577408 inhabitants (on January 1st, 2003), and is subdivided in seven provinces with 60 hospitals and about 20000 beds for acute care. Five consecutive heatwaves (three or more consecutive days with Humidex above 40 degrees C) occurred during summer 2002 and 2003 in the region. From the regional computerized archive of hospital discharge records, we extracted the daily count of hospital admissions for people aged >or=75, from June 1 through August 31 in 2002 and 2003. Among people aged over 74 years, daily hospital admissions for disorders of fluid and electrolyte balance, acute renal failure, and heat stroke (grouped in a single nosologic entity, heat diseases, HD), respiratory diseases (RD), circulatory diseases (CD), and a reference category chosen a priori (fractures of the femur, FF) were independently analyzed by Generalized Estimating Equations.
  
  
  RESULTS
  Heatwave duration, not intensity, increased the risk of hospital admissions for HD and RD by, respectively, 16% (p < .0001) and 5% (p < .0001) with each additional day of heatwave duration. At least four consecutive hot humid days were required to observe a major increase in hospital admissions, the excesses being more than twofold for HD (p < .0001) and about 50% for RD (p < .0001). Hospital admissions for HD peaked equally at the first heatwave (early June) and last heatwave (August) in 2004 as did RD. No correlation was found for FF or CD admissions.
  
  
  CONCLUSIONS
  The first four days of an heatwave had only minor effects, thus supporting heat health systems where alerts are based on duration of hot humid days. Although the finding is based on a single late summer heatwave, adaptations to extreme temperature in late summer seem to be unlikely.
authors: Department of Environmental Medicine and Public Health, University of Padova, Padova, Italy. giuseppe.mastrangelo@unipd.it
authors: Giuseppe
authors: G
authors: Mastrangelo
authors: Ugo
authors: U
authors: Fedeli
authors: Cristiana
authors: C
authors: Visentin
authors: Giovanni
authors: G
authors: Milan
authors: Emanuela
authors: E
authors: Fadda
authors: Paolo
authors: P
authors: Spolaore
mesh_terms: D000368:Aged; D002980:Climate; D016001:Confidence Intervals; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006359:Heat Exhaustion / Q000150:complications / Q000453:epidemiology* / Q000628:therapy; D006760:Hospitalization / Q000706:statistics & numerical data / Q000639:trends*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D006813:Humidity / Q000009:adverse effects; D007558:Italy / Q000453:epidemiology; D008297:Male; D012621:Seasons; D013997:Time Factors; D014883:Water-Electrolyte Imbalance / Q000209:etiology
references: Am J Respir Cell Mol Biol. 1991 Jan;4(1):72-81
references: 1846079
references: Am Rev Respir Dis. 1989 Jan;139(1):56-61
references: 2912357
references: Lancet. 1993 Dec 4;342(8884):1397-9
references: 7901686
references: Am J Respir Crit Care Med. 1996 Mar;153(3):904-9
references: 8630571
references: Environ Res. 1995 Aug;70(2):105-13
references: 8674478
references: J Epidemiol Community Health. 1996 Apr;50 Suppl 1:s47-51
references: 8758224
references: J Epidemiol Community Health. 1996 Apr;50 Suppl 1:s76-80
references: 8758229
references: Environ Health Perspect. 1997 Jan;105(1):84-93
references: 9074886
references: BMJ. 1997 Jun 7;314(7095):1658-63
references: 9180068
references: Environ Res. 1998 Apr;77(1):9-19
references: 9593623
references: Int J Biometeorol. 1998 Aug;42(1):44-50
references: 9780845
references: Am J Prev Med. 1999 May;16(4):269-77
references: 10493281
references: Int J Biometeorol. 2004 Nov;49(2):91-7
references: 15549422
references: Am J Respir Crit Care Med. 2005 Mar 15;171(6):627-31
references: 15579726
references: Health Stat Q. 2005 Spring;(25):6-11
references: 15804164
references: Stroke. 2005 May;36(5):1031-4
references: 15790948
references: Environ Res. 2005 Jul;98(3):390-9
references: 15910795
references: Med Hypotheses. 2006;66(5):1025-8
references: 16413137
references: Environ Res. 1988 Apr;45(2):224-41
references: 3349975
references: Am J Forensic Med Pathol. 2001 Dec;22(4):352-7
references: 11764901
references: N Engl J Med. 2002 Jun 20;346(25):1978-88
references: 12075060
references: J Epidemiol Community Health. 2002 Jul;56(7):536-7
references: 12080162
references: Epidemiol Rev. 2002;24(2):190-202
references: 12762092
references: Occup Environ Med. 2004 Nov;61(11):893-8
references: 15477282
references: Int J Biometeorol. 1971 Mar;15(1):23-39
references: 5088561
references: Environ Health Perspect. 1991 Dec;96:145-50
references: 1820257