Platelet count and indoor cold exposure among elderly people: A cross-sectional analysis of the HEIJO-KYO study

Abstract

BackgroundExcess mortality from cardiovascular disease during cold seasons is a worldwide issue. Although some physiologic studies suggests that platelet activation via cold exposure may cause an increased incidence of cardiovascular disease in winter, the influence of indoor cold exposure in real-life situations on platelet (PLT) count remains unclear.MethodsA cross-sectional study was conducted among 1095 elderly individuals. After obtaining a venous sample in the morning, indoor temperature of participants' home was measured every 10 min for 48 h. The mean indoor temperature while the participants stayed at home was calculated. All measurement was conducted during cold seasons (October to April) from 2010 to 2014.ResultsThe mean age of the 1095 participants was 71.9 years. They spent 87.3% of the day at home (20 h 27 min). A 1 °C lower daytime indoor temperature was associated with a significant increase in PLT count of 1.47 × 109/L (95% confidence interval, 0.39–2.56 × 109/L). Compared with the warmest tertile group (20.1 [standard deviation {SD}, 0.09] °C), the coldest group (11.7 [SD, 0.12] °C) showed a 5.2% higher PLT count (238.84 [SD, 3.30] vs. 226.48 [SD, 3.32] × 109/L; P = 0.01), even after adjusting for basic characteristics (age, gender, body weight, and smoking), antihypertensive medication, comorbidities (diabetes, estimated glomerular filtration rate), socioeconomic status (household income and education), day length, and outdoor temperature.ConclusionsWe found a significant and independent association between lower indoor temperature and higher PLT count among elderly in winter.

A Review of the Relation between Household Indoor Temperature and Health Outcomes

“…This means that most studies take into consideration the influence and interconnection with outdoor temperatures or climate (link 1). The higher relevance assigned to socioeconomic factors-indoor temperature and indoor temperature-health outcome (links 4 and 5) socioeconomic factor-indoor temperature [27,29,[39][40][41][42][43][44][45][46][47][48][49][50] Energies 2020, 13, x FOR PEER REVIEW 7 of 23…”

“…The influence of outdoor temperatures on the indoor environment has been assessed in studies such as Uejio et al [39] and Osman et al [40]. Several studies such as [41][42][43][44] have stressed that indoor temperatures were more significantly related to a given health indicator than the outdoor temperature.…”

“…Most of the indicators categorised as "other health indicators" seem to be interconnected to other categories, namely for cardiovascular health conditions. For example, hypertension, mean arterial or blood pressure, and platelet count have been either mentioned or used as different health biomarkers in studies that aim to associate low indoor temperatures to health biomarkers for cardiovascular conditions (e.g., References [41,43,49,50]). Whereas respiratory cases have been in terms of relevance the second most assessed health condition with the least amount links to "other health indicator" categories.…”

“…Since exposure to inadequate indoor temperatures (too cold or too hot) may imply adverse health impacts, some studies have suggested that through the improvement of indoor temperatures, health gains for householders could be achieved (e.g., References [41][42][43]). Therefore in Figure 6, health outcomes departing from inadequate indoor temperature are related to warmth/cool EE pathway.…”

“…Table 1 presents the studies addressing each one of the links described in Figure 3 and 264 summarises the identified energy efficiency-indoor temperature-health outcomes. [22] energy efficiency upgrade-low indoor temperature-emergency hospital admissions cardiovascular and respiratory conditions and injuries [27] energy efficiency upgrade-low indoor temperature-cardiovascular and respiratory health related conditions outdoor temperature-cardiovascular and respiratory-related mortality and morbidity [29] high indoor temperature-emergency hospital admissions cardiovascular and respiratory conditions; psychosocial impacts [39] low indoor temperature-emergency care for cardiovascular and respiratory conditions [40] low indoor temperature-cardiovascular and mental health related biomarkers [41] low indoor temperature-cardiovascular and mental health related biomarkers [42] low indoor temperature-cardiovascular and mental health related biomarkers [43] low indoor temperature-cardiovascular related biomarkers [44] high indoor temperature-heat-related health symptoms [45] low indoor temperature-long term health disabilities [46] energy efficiency upgrades-low indoor temperature cardiovascular and respiratory-related mortality [47] energy efficiency upgrade-low indoor temperature general health; respiratoryrelated conditions and general practitioner's hospital admissions [48] energy efficiency upgrade-low indoor temperature-respiratory related conditions, general health status hospital admissions [49] low indoor temperature-cardiovascular related biomarkers [50] low indoor temperature-cardiovascular related biomarkers…”