The relationship between inside and outside ambient temperatures in Christchurch, New Zealand

Evaluation of Diagnostic Codes in Morbidity and Mortality Data Sources for Heat-Related Illness Surveillance

OBJECTIVES

The primary objective of this study was to identify patients with heat-related illness (HRI) using codes for heat-related injury diagnosis and external cause of injury in 3 administrative data sets: emergency department (ED) visit records, hospital discharge records, and death certificates.

METHODS

We obtained data on ED visits, hospitalizations, and deaths for Florida residents for May 1 through October 31, 2005-2012. To identify patients with HRI, we used codes from the International Classification of Diseases, Ninth Revision, Clinical Modification ( ICD-9-CM) to search data on ED visits and hospitalizations and codes from the International Classification of Diseases, Tenth Revision ( ICD-10) to search data on deaths. We stratified the results by data source and whether the HRI was work related.

RESULTS

We identified 23 981 ED visits, 4816 hospitalizations, and 140 deaths in patients with non-work-related HRI and 2979 ED visits, 415 hospitalizations, and 23 deaths in patients with work-related HRI. The most common diagnosis codes among patients were for severe HRI (heat exhaustion or heatstroke). The proportion of patients with a severe HRI diagnosis increased with data source severity. If ICD-9-CM code E900.1 and ICD-10 code W92 (excessive heat of man-made origin) were used as exclusion criteria for HRI, 5.0% of patients with non-work-related deaths, 3.0% of patients with work-related ED visits, and 1.7% of patients with work-related hospitalizations would have been removed.

CONCLUSIONS

Using multiple data sources and all diagnosis fields may improve the sensitivity of HRI surveillance. Future studies should evaluate the impact of converting ICD-9-CM to ICD-10-CM codes on HRI surveillance of ED visits and hospitalizations.

Triggering of stroke by ambient temperature variation: a case-crossover study in Maputo, Mozambique

OBJECTIVES

The effect of ambient temperature as a stroke trigger is likely to differ by type of stroke and to depend on non-transient exposures that influence the risk of this outcome. We aimed to quantify the association between ambient temperature variation and stroke, according to clinical characteristics of the events, and other risk factors for stroke.

METHODS

We conducted a case-crossover study based on a 1-year registry of the hospital admissions due to newly occurring ischemic and hemorrhagic stroke events in Maputo, Mozambique's capital city (N=593). The case-period was defined as the 7 days before the stroke event, which was compared to two control periods (14-21 days and 21-28 days before the event). We computed humidity- and precipitation-adjusted odds ratios (OR) and 95% confidence intervals (95%CI) using conditional logistic regression.

RESULTS

An association between minimum temperature declines higher than 2.4 °C in any two consecutive days in the previous week and the occurrence of stroke was observed only for first events (OR=1.43, 95%CI: 1.15-1.76). Stronger and statistically significant associations were observed for hemorrhagic stroke (OR=1.50, 95%CI: 1.07-2.09) and among subjects not exposed to risk factors, including smoking, high serum cholesterol or atrial fibrillation. No differences in the effect of temperature were found according to the patients' vital status 28 days after the event.

CONCLUSIONS

First stroke events, especially of the hemorrhagic type, were triggered by declines in the minimum temperature between consecutive days of the preceding week.

Involving students in real-world research: a pilot study for teaching public health and research skills

BACKGROUND

There is some evidence that medical students consider population health issues less important than other domains in the health sciences and attitudes to this field may become more negative as training progresses. A need to improve research skills among medical students has also been suggested. Therefore we piloted an integrative teaching exercise that combined teaching of research skills and public health, with real-world research.

METHODS

Third year medical students at the University of Otago (Dunedin, New Zealand) filled in a questionnaire on their housing conditions and health. The students were given the results of the survey to discuss in a subsequent class. Student response to this teaching exercise was assessed using a Course Evaluation Questionnaire.

RESULTS

Of the 210 students in the class, 136 completed the Course Evaluation Questionnaire (65%). A majority of those who responded (77%) greatly supported or supported the use of the survey and seminar discussion for future third year classes. Most (70%) thought that the session had made them more aware and concerned about societal problems, and 72% felt that they now had an improved understanding of the environmental determinants of health. Students liked the relevance and interaction of the session, but thought it could be improved by the inclusion of small group discussion. The findings of the students' housing and health were considered by the tutors to be of sufficient value to submit to a scientific journal and are now contributing to community action to improve student housing in the city.

CONCLUSION

In this pilot study it was feasible to integrate medical student teaching with real-world research. A large majority of the students responded favourably to the teaching exercise and this was generally successful in raising the profile of public health and research. This approach to integrated teaching/research should be considered further in health sciences training and continue to be evaluated and refined.

Risk factors for mold in housing: a national survey

A national random telephone survey was undertaken to determine the prevalence of reported mold in New Zealand houses and the risk factors for it. A total of 613 households provided responses. Mold in one or more rooms was reported by 35.1% of respondents in the sample. House design and construction factors that were independently associated with reported mold in the multivariate analysis included: poorer house condition, older house age (>22 years), relative lack of sun exposure, and having no insulation (e.g. for poorer house condition: odds ratio=1.97, 95% CI=1.25, 3.11). Univariate analyses also showed increased risk associated with high locality rainfall, and living in the most northern part of the country. The number of residents was significantly associated with reported mold in the multivariate analysis as were various behaviors in the univariate analysis (i.e. frequency of baths, showering and clothes washing). The high prevalence of unflued gas heating (32.9%) found in this sample is of potential concern given the potential respiratory hazards. Although this survey has a number of limitations, it does suggest that there are a number of potentially modifiable risk factors for mold that could be reduced by a range of policy responses.

PRACTICAL IMPLICATIONS

While further research is desirable, the available evidence associated with the health and other adverse impacts of both mold and dampness would favor additional policy responses by government. These could include changes to regulations around housing design including house position, access to sunlight, and level of insulation. The extension of low interest loans for insulation or subsidized installation can help to increase its level of use. Restrictions on the sales of unflued gas heaters could also be considered. A mass media campaign could also be used to inform the population of the readily modifiable risk factors for mold growth and dampness.

Thermal insulation and SIDS-an investigation of selected 'Eastern' and 'Western' infant bedding combinations

BACKGROUND

Differences in the incidence of SIDS between 'Western' and 'Eastern' countries has been attributed to cultural practices, which may affect the infants care and thermal environment.

AIM

The purpose of this work was to estimate for selected 'commonly' used bedding, sleep positions and practices in Japan, Korea and New Zealand, the intrinsic 'dry' thermal resistance of bedding. Insulation levels are also discussed in the context of published information about the thermal environment in which the bedding is likely to be used.

METHOD

Selected Japanese, Korean and New Zealand bedding was loosely tucked over an infant manikin in the lateral, prone and supine sleep positions. Thickness in use was measured, and intrinsic 'dry' thermal resistance estimated using the Wilson Laing model which accommodates the effect on insulation of the three-dimensional arrangement of bedding combinations during use.

RESULTS AND DISCUSSION

Thickness of under- and upper-bedding varied among countries with thickness and estimated 'dry' thermal resistance of the upper-bedding affected by the type/combination of bedding and the infants sleep position. Insulation levels are discussed in relation to environmental conditions within and among countries and between seasons. Further information on thermal environments, bedding combinations used and care practices within both Asian and Western countries is needed.

CONCLUSIONS

'Eastern' infants appear likely to be generally covered in bedding combinations of greater insulation than those used to cover 'Western' infants in comparable seasons. Differences existed between insulation of the Japanese and Korean bedding combinations investigated. Lower rates of SIDS apparent in 'Asian' populations do not appear attributable to use of lower levels of bedding insulation only.

Infant Weight and Gestational Age Effects on Thermoneutrality in the Home Environment

OBJECTIVE

To describe infant temperature in the home environment and explore factors, particularly weight and gestational age at birth, associated with maintenance of thermal neutral temperatures in the home.

DESIGN

Continuous abdominal skin temperature was recorded at 1-minute intervals for a 24-hour period in both full-term and preterm infants, using a two-group exploratory design.

SETTING

Infants were studied in the home environment.

PATIENTS/PARTICIPANTS

Twenty-four preterm and 16 full-term infants were studied at approximately 44 weeks postconceptional age.

MAIN OUTCOME MEASURES

Abdominal skin temperature was coded as within, over, or under the thermal neutral zone, and the percentage of time in these thermal conditions was calculated.

RESULTS

Regression analysis was conducted, and weight, gestational age, and weight by gestational age interaction were found to be statistically significant predictors of percent of time over and under the thermal neutral zone. Smaller preterm infants were overheated, whereas heavier preterm infants were underheated. Smaller full-term infants were underheated, and heavier full-term infants were overheated.

CONCLUSION

Thermal care of infants in the home may be influenced by parental perception of thermal vulnerability relative to weight and gestational age at birth.