May 29, 2012

One in three households misreports smoke alarm coverage

One in three households in Baltimore misreports its smoke alarm coverage, with the vast majority of errors due to overreporting it, according to a study by researchers from the Johns Hopkins Center for Injury Research and Policy.

Reasons for overreporting included study participants’ incorrectly assuming that all their alarms were working because they weren’t beeping, and not having alarms on every level of the home.

Previous research has found varying validity for self-reporting of smoke alarm coverage, but this study is unique for also examining the reasons why individuals misreport. The study is available online in advance of publication in the journal Injury Prevention.

“Forty percent of all residential fire deaths in the U.S. occur in homes with no smoke alarms, and another 23 percent occur in homes where an alarm is present but not functioning,’’ said study author Wendy Shields, an assistant scientist with the Center for Injury Research and Policy, part of the university’s Bloomberg School of Public Health. ‘‘Our study suggests relying upon self-reports of smoke alarm coverage is not an accurate way to measure whether homes are protected.’’

The National Fire Protection Association recommends that all residential homes have a smoke alarm in every bedroom, outside every sleeping area and on every level of the home.

Shields and colleagues conducted interviews and home observations in more than 600 households selected from 12 census tracts in eastern Baltimore, a relatively low-income urban area. After respondents completed the questions on fire-safety behaviors, data collectors tested the functionality of all smoke alarms in the house. A small sample of the overreporters were contacted by phone and asked a series of questions aimed at better understanding reasons for overreporting.

“Despite the small number of follow-up respondents, the phone interviews give us some important insights,’’ said Andrea Gielen, director of the Johns Hopkins Center for Injury Research and Policy and senior author of the report. ‘‘Particularly troubling is the fact that one in three of the follow-up respondents indicated they reported greater coverage than they actually had because they knew they should.’’

This social desirability bias occurred despite the fact that respondents had been informed that data collectors would be testing alarms in the home as part of the interview.

‘‘The implication for both researchers who survey residents and firefighters who canvass communities is that it’s critical to confirm smoke alarm status with actual testing of the alarms,’’ Gielen said.

In conclusion, Shields said, ‘‘Given the huge public health toll of residential fires in the U.S., every effort should be made to keep people safe in their homes. Public education efforts should include specific instructions on how to check alarm functionality and on the importance of having an alarm on every level of the house. More widespread use of the new 10-year lithium battery alarms would also make it easier for residents to keep their homes and families protected,’’ she said.

Additional authors of the study are Rebecca Stepnitz and Eileen McDonald, both of Johns Hopkins.

Support for this research was provided to the Johns Hopkins Center for Injury Research and Policy by grants from the National Center for Injury Prevention and Control at the Centers for Disease Control and Prevention, and the National Institute of Child Health and Human Development.