Table 2 Probabilities used in the medicinal poisonings model

pSafe

Baseline prevalence of safe storage of medicines

Case control study of risk and protective factors for poison injuries in under 5 year olds (Kendrick et al, paper om press).

Number of households with safe storage of medicines/Total number of households selected as community controls in case control of risk and protective factors in children under 5 years old (Kendrick et al, paper om press).

1527/2033 = 0.75

Beta

pAccept

Probability of accepting the intervention

Saramago, Cooper et al., 2015 [14]

Assumption based on value in Functional smoke alarm model. Assumed the same for all interventions.

0.90

Fixed

pEff

Probability of safe storage of medicines given the intervention

Achana et al., 2015 [9]

(1) Usual care

(2) Education

(3) Provision of low cost/free low cost/free equipment

(4) Education + provision of low cost/free equipment

(5) Education + equipment + home safety inspection

(6) Education + equipment + fitting

(7) Education + equipment + home safety inspection + fitting

0.87 (95%CrI 0.56, 0.98)

0.90 (95%CrI 0.61, 0.98)

0.93 (95%CrI 0.65, 0.99)

0.94 (95%CrI 0.74, 0.99)

0.90 (95%CrI 0.56, 0.99)

0.90 (95%CrI 0.59, 0.98)

0.93 (95%CrI 0.66, 0.99)

Posterior distribution of absolute intervention effects from network meta-analysis.

pIngest

Probability of unintentional exposure/ingestion

Orton et al., 2014 [10]

Tyrrell et al., 2012 [33]

Office for National Statistics, 2013 [34]

Orton et al [10] – incidence of poisonings in the UK for period 2005–2009 is 30.1 (95 % CI 29.1–31.2). Mid-year population estimates of under 5 year olds in the UK in 2012 = 3996400 [34]. Hence number of poisoning cases = (30.1*3996400)/10000 = 12029. The numerator (n = 12029*0.6 = 7217) was derived based on information in [33] suggesting that 1316 (60 %) of the 2193 medically reported poisonings identified in the THIN database were due to ingestion of a medicinal substance.

7217/3996400 = 0.001806

Beta

orIngest

Relative risk of exposure to a medicinal substance comparing children with a poisoning to community controls.

Case control study of risk and protective factors for poison injuries in under 5 year olds (unpublished study)

Community controlled adjusted analysis odds ratio for safe storage versus no safe storage = 1.83 (95 % CI 1.38–2.42)

Log odds ratio (SE) = -0.604 (0.143)

Normal

pAmb

Probability of using emergency ambulance.

Hospital Episode Statistics, 2012

Hospital Episode Statistics (2012b): 24.2 % of all cases arrived by emergency transfer (ambulance/helicopter).

0.242

Fixed

pAdmit

Probability of in-patient admission following a medicinal poisoning injury (ICD-10: X40-X44).

Hospital Episode Statistics, 2013 [35]

Office for National Statistics, 2013 [34]

Hospital Episode Statistics, 2012–2013) [35]: Number of poisoning cases (X40-X44) admitted in 0–4 years olds (period 2012–2013) in England = 3909. Scaled up by a factor of 1.163 (i.e. 3909*1.163 = 4546 cases for whole of UK) based on mid-2012 population estimates for UK and England [34].

4546/7217 = 0.63

Beta

pSevere

Probability of severe poisoning injury

Mowry et al., 2013 [36]

NPDS 2012 report [36], Table 13, page 968) 1.91 % of major poisoning cases (across all age groups) resulted in a chronic health condition. Numerator = 0.019* 4546 = 87.

87/4546 = 0.0191

Beta

pFatal

Probability of fatal poisoning injury.

Office for National Statistics, 2012 [37]

UK mortality statistics [37]. 1 fatality from medicinal poisonings in 0–4 years old (assumed fatality occur after a long inpatient stay).

1/86 = 0.0116

Beta

pDead

UK mortality statistics

Office for National Statistics, 2010 [38]

UK mortality statistics [38]

Normal