An evaluation of thermostatic mixer
valves to reduce bath water
temperature in homes of families
with young children living in social
housing
Denise Kendrick
Professor of Primary Care Research
University of Nottingham
Jane Stewart
Senior Research Fellow
Nottinghamshire Healthcare Trust
(NHS Nottinghamshire County)
And co- authors
The problem – bath hot tap water
scalds in young children
• Each year 2,000 ED attendances, 500
admissions
• Most admissions children < 5years
• Steep social gradient
– most deprived most vulnerable
• Domestic hot water temperatures can scald
in about a second
• Cost of severe scald ~ £250 000
What is a Thermostatic Mixer Valve
(TMV)?
• Engineering solution to reduce
the temperature of hot bath tap
water temperature
• No active participation by parents required
• Mixes hot and cold bath tap water to pre-set
temperature - 46 ºC
• Takes 6 hours for a scald at this temperature
Aims of the study
• To assess TMVs for their:
• Effectiveness and cost effectiveness in reducing
bath hot water temperature
• Acceptability to families
• Impact on bath time safety practices
– In families with children under the age of 5 years living
in social housing
Methods
• Randomised controlled trial
– Questionnaire at baseline
• Delivered the intervention
– TMV
– Educational leaflet
– Laminated leaflet on how to use TMV
– Water temperature checks at baseline,
3 and 12 months
– Questionnaire at 12 months follow up
• Fieldwork in Glasgow
Participants
124 families completed
baseline questionnaire
Intervention arm
62
(46 TMVs fitted)
Control arm
62
Water temps: baseline n=23
3 months n=15
12 months n=16
Water temps: baseline n=27
3 months n=15
12 months n=15
12 month questionnaire
44 still tenants/participating
12 month questionnaire
49 still tenants/participating
40 returned
(91.9%)
40 returned
(81.6%)
Characteristics of participants
Characteristics
Intervention arm
n=62
Control arm
n=62
Mother completed questionnaire
57 (91.9)
58 (93.6)
Single adult household
40 (64.5)
47 (75.8)
Number of children in the home
1
2
29 (46.8)
21 (33.9)
25 (40.3)
26 (41.9)
38 (73.1) [10]
43 (72.9) [3]
Number of adults in paid
employment
0
1
39 (65.0) [2]
16 (26.7)
40 (65.6) [1]
17 (27.9)
Family receives state benefits
50 (82.0) [1]
56 (90.3)
Ethnic group of respondent
White Scottish
Black African
54 (88.5) [1]
6 (9.8)
54 (88.5) [1]
3 (4.9)
Age respondent left full time
education
≤16
[ ] missing values
Acceptability of bath hot tap water
(baseline)
Intervention
arm
Satisfaction (number (%))
Very happy or happy with bath
hot tap water temperature
Bath water is:
Very hot – need to add a lot of
cold water to the bath
Hot – need to add some cold
water to the bath
[ ] missing values
Control arm
n=62
n=62
39 (62.9)
37 (59.7)
41 (67.2) [1]
38 (61.3)
19 (31.2)
24 (38.7)
Bath time safety practices
(baseline)
Safety practices
Intervention
arm n=62
Control arm
N=62
2 (3.2)
9 (14.8) [1]
54 (88.5) [1]
54 (88.5) [1]
Child has been left alone in the
bath
27 (43.6)
13 (21.0)
Child has been left alone in
bathroom whilst bath is running
19 (30.7)
12 (19.4)
Runs bath using cold water first
Bath water temperature
checked for every bath
[ ] missing values
100
90
80
70
60
50
40
40
50
60
70
80
90
3 month water temperature (degrees Celsius)
100
Hot bath tap water temperatures at
baseline, 3 and 12 months
Intervention arm
Control arm
90
80
70
60
50
40
12 month water temperature (degrees Celsius)
100
Control arm
Control arm
Intervention arm
Intervention arm
Were parents satisfied with the TMV?
Intervention arm responders with
TMV fitted (n=34)
Very happy or happy with TMV
30 (88.2)
Would recommend TMV to a friend
28 (87.5) [2]
Would not be happy if kitchen and
bath hot tap water were same
temperature
23 (69.7) [1]
Since having TMV…
Child less likely to be scalded
32 (94.1)
Doesn’t take longer to run bath
22 (68.8) [2]
Easier to control bath water
temperature
29 (90.6) [2]
Bath water isn’t hot enough
12 (36.4) [1]
Can no longer top up bath with hot
water whilst in the bath
9 (27.3) [1]
Acceptability of bath hot tap water
(follow up)
Intervention
arm
Responders
n=40 (%)
Very happy or happy with
bath hot tap water
temperature
Bath water is:
Very hot – need to add a lot
of cold water to the bath
Hot – need to add some cold
water to the bath
Warm enough - don’t need to
add any cold water to the
bath
32 (82.1)
[1]
7 (18.0)
[1]
16 (41.0)
14 (35.9)
Control arm
Responders
n=40 (%)
23 (57.5)
Relative Risk
(95% CI)
1.43
(1.05, 1.93)
22 (55.0)
18 (45.0)
0 (0.0)
0.33
(0.16, 0.68)†
Bath time safety practices
Intervention
arm
responders
n=40(%)
Runs bath using cold water first*
Bath water temperature checked for
every bath
Child has been left alone in the
bath*
Child has been left alone in
bathroom whilst bath is running*
(follow up)
Control arm
responde
rs
n=40(%)
Relative Risk
(95% CI)
5 (12.5)
11 (27.5)
0.55 (0.22,
1.39)
32 (84.2) [2]
40 (100.0)
0.84 (0.73,
0.97)
13 (32.5)
8 (20.5) [1]
1.11 (0.51,
2.41)
12 (30.8) [1]
9 (22.5)
1.28 (0.62,
2.68)
Health economic analysis
Professor Ceri Phillips - Swansea University
•NHS costs to treat a scald –
•range from £25, 226 - £71, 902
• Cost-effectiveness analysis indicated a
potential saving to the NHS of
£3, 229, 008
• £1.41 saved for every £1 spent
Summary
• TMVs are effective in reducing bath hot
tap water temperature
• Majority of parents satisfied with the
TMV and the temperature
• Would recommend a TMV to a friend
• Feel child less likely to be scalded
• However, parents checking temperature
of bath water less often
• A third of people reported bath water
not hot enough
Implications
• Suggests that parents are willing to
trade some inconvenience for increased
safety
• TMVs should be considered as a scald
prevention intervention for families with
children
• Important to reinforce bath time safety
messages about checking the water
temperature and leaving children alone
in the bath
• Cost effective solution – requires
interagency working – spend money in
one sector to save money in another
Funding
• Policy Research Programme (PRP) at the
Department of Health -Accidental Injury
Prevention Research Initiative (001/0009)
• The final study design, data collection, analysis, interpretation of
results, and paper writing was the sole responsibility of the authors.
The views and opinions expressed in this paper do not necessarily
reflect those of the funding body. This is an independent report
commissioned and funded by the Policy Research Program in the
Department of Health. The views expressed are not necessarily those
of the Department.
Thank you
for
listening!
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