Brief reportSmoke Alarm and Battery Function 42 Months After Installation: A Randomized Trial
Introduction
Smoke alarms are among the most effective interventions to reduce residential fire deaths.1, 2, 3, 4, 5, 6 Three RCTs7, 8, 9 have been conducted to identify the types of smoke alarms most likely to function up to 15 months after installation. All three studies compared the functionality of the two most common types of commercially available smoke alarms: ionization and photoelectric. Two of the studies also examined battery types and smoke alarm function. However, previous trials have not had sufficient follow-up periods to test the long-term function of battery types. This analysis follows the households from one of these randomized trials for 3.5 years (a previous analysis followed households for 1 year)—more than twice the length of previous studies9 to determine the alarm functionality.
Section snippets
Methods
Data were analyzed from an extended follow-up period for a previously published randomized trial,9 where details of the study methods and CONSORT diagram can be found. In summary, participants were recruited between July 2003 and June 2004 from an existing prospective cohort study.9, 10 Both the original cohort study and the smoke alarm trial were approved by the University of Iowa IRB. Participants were randomized using a sequential random number table into one of four smoke alarm/battery
Results
A total of 691 households were eligible for the 42-month follow-up visit. Excluded were 27 (3.9%) that could not be contacted after multiple efforts; 10 (1.4%) that were unoccupied; 6 (0.9%) whose owners no longer wished to participate; and 3 (0.4%) who had installed hard-wired alarms. Of 645 households visited, 12 (1.7%) were excluded because smoke alarm function data were not obtained or recorded. This analysis includes the remaining 633 households, which means 91.6% were involved in
Discussion
After 3.5 years, more than 90% of homes in this rural cohort had at least one functional smoke alarm, and more than 81% of alarms functioned. An earlier study8 found a similar proportion of functioning alarms, 84.2%, after 15 months. Another study,7 however, found that only 54.4% of homes had a functioning alarm, and 51.1% of study smoke alarms still functioned after 15 months. The only other study12 to examine long-term smoke alarm function in five states found that only 33% of the study's
Conclusion
The combination of photoelectric alarms with lithium batteries was the most likely smoke alarm/battery combination to function 3.5 years after installation, and the least likely combination to have nuisance alarms.
References (13)
- et al.
Smoke alarms by type and battery life in rural households: a randomized controlled trial
Am J Prev Med
(2008) - et al.
Fatal residential fires: who dies and who survives?
JAMA
(1998) The U.S. experience with smoke detectors: who has them? How well do they work? When don't they work?
NFPA J
(1994)- et al.
Risk factors for fatal residential fires
N Engl J Med
(1992) - et al.
Smoke alarms and prevention of house-fire–related deaths and injuries
West J Med
(2000) Smoke detectors essential for safety
Consum Rep
(1994)