User-driven design of child restraint information to reduce errors in use: a pilot randomised controlled trial

Abstract

BackgroundIncorrect use of child restraints is a long-standing problem that increases the risk of injury in crashes. We used user-centred design to develop prototype child restraint instructional materials. The objective of this study was to evaluate these materials in terms of comprehension and errors in the use of child restraints. The relationship between comprehension and errors in use was also explored.MethodsWe used a parallel-group randomised controlled trial in a laboratory setting. The intervention group (n=22) were provided with prototype materials and the control group (n=22) with existing instructional materials for the same restraint. Participants installed the restraint in a vehicle buck, secured an appropriately sized mannequin in the restraint and underwent a comprehension test. Our primary outcome was overall correct use, and our secondary outcomes were (1) comprehension score and (2) percent errors in the installation trial.ResultsThere was 27% more overall correct use (p=0.042) and a higher mean comprehension score in the intervention group (mean 17, 95% CI 16 to 18) compared with the control group (mean 12, 95% CI 10 to 14, p<0.001). The mean error percentage in the control group was 23% (95% CI 16% to 31%) compared with 14% in the intervention group (95% CI 8% to 20%, p=0.056). For every one point increase in comprehension, there was an almost 2% (95% CI −2.7% to −1.0%) reduction in errors (y=45.5–1.87x, p value for slope <0.001).ConclusionsConsumer-driven design of informational materials can increase the correct use of child restraints. Targeting improved comprehension of informational materials may be an effective mechanism for reducing child restraint misuse.

A Process Evaluation Protocol for Examining the Impact of Instructions for Correct Use of Child Car Seats Designed through a Consumer-Driven Process and Evaluated in a Field-Based Randomised Controlled Trial

“…We found a significantly higher level of comprehension of key information related to correct use among those exposed to the prototype material than those exposed only to existing materials, and a significant linear relationship between the comprehension of this information and correct use of the restraint. Using a stringent, realistic measure of errors likely to have a significant deleterious effect on crash protection, we demonstrated a 27% reduction in errors among those exposed to the prototype compared to those exposed to existing materials [18]. While this impact on correct use is promising, it was achieved under controlled laboratory conditions with a participant population not entirely representative of child restraint users.…”

“…A small number of studies have examined the potential of redesigned information supplied with child restraints as a measure to reduce errors in use [15][16][17][18]. Two of these have focused solely on the design of labels fixed to the restraint [16,17], one focused on written instructions and labels fixed to the restraint [15], and most recently, we developed an enhanced set of materials incorporating written instructions, labels and video [18].…”

“…A small number of studies have examined the potential of redesigned information supplied with child restraints as a measure to reduce errors in use [15][16][17][18]. Two of these have focused solely on the design of labels fixed to the restraint [16,17], one focused on written instructions and labels fixed to the restraint [15], and most recently, we developed an enhanced set of materials incorporating written instructions, labels and video [18]. Generally, these studies have found improvement in some areas of correct child restraint use; however, only the work by Kramer et al [17] and Hall et al [18] achieved significant effects of re-design over current information on correct restraint use in laboratory-based trials.…”

“…Two of these have focused solely on the design of labels fixed to the restraint [16,17], one focused on written instructions and labels fixed to the restraint [15], and most recently, we developed an enhanced set of materials incorporating written instructions, labels and video [18]. Generally, these studies have found improvement in some areas of correct child restraint use; however, only the work by Kramer et al [17] and Hall et al [18] achieved significant effects of re-design over current information on correct restraint use in laboratory-based trials. One key difference in the design process between those demonstrating some significant effect on correct use and those that did not was the inclusion of an iterative consumer-driven design step in the process of developing materials.…”

“…In our recent work [18], we used the Sless and Wisemen model [19] to develop a set of materials, which we evaluated in a randomised controlled pilot trial in the laboratory. We found a significantly higher level of comprehension of key information related to correct use among those exposed to the prototype material than those exposed only to existing materials, and a significant linear relationship between the comprehension of this information and correct use of the restraint.…”