1. r u HAPI? Random sampling to monitor pressure injury prevalence
Andrew Jull 1, 2, Matt Chappell 1, Elaine McCall 1, Sam Tobin 1 1 Auckland District Health Board, 2 University of Auckland, New Zealand
Background
Results
Auckland District Health Board has a campus of hospitals providing secondary and tertiary services. Reducing hospital-acquired pressure injuries (HAPI) has been a key quality improvement goal, but pressure injury surveillance poses some difficult problems:[1]
Pressure injuries can be either hospital-acquired (incident) or present on admission (prevalent), but many surveys do not differentiate between the two.
Inclusion of pressure injuries present on admission will over-estimate prevalence while exclusion of minor (Grade 1) pressure injuries will under-estimate prevalence.
Frequent monitoring is required for improvement purposes. Whole-hospital surveys are burdensome leading to infrequent surveys, which do not suit monitoring for improvement.
Results results from infrequent measurement may be influenced by seasonality and other confounders.
Incident reporting systems or sophisticated interrogation of electronic medical records can be used for more frequent monitoring, but both are reliant on self-reporting and will be inaccurate.[2]
Prevalence estimates will vary without standardised definitions and agreement on how “ungradable” pressure injuries will be counted.
To February 2016, 11,247 patients were audited over the four years: 2710 in year 1, 2745 in year 2, 2819 in year 3, 2973 in year 4.
The audit sample represents 25% of the eligible 44,527 patients present on each audit day. The average audit sample size was 234 patients per month. Random sampling has delivered a representative cross-section of the hospital census on each audit day (Table 1), albeit with oversampling of children (an artifact of our approach – about 20% of participating clinical units are children’s wards).
980 HAPI were observed on 635 patients over the four years. Pressure injuries occurred in all age groups over the four years with the distribution a J-shaped curve (Figure 1). The injuries were predominantly grades 1 and 2 (98.1%), with grade 1 the most frequent (79.5%). Grade 3 and 4 HAPI were rare (respectively 1.3% and 0.6% of injuries). 80% of HAPI occurred on the sacrum, heel, ankle, elbow, nose, and ear.
228 patients with HAPI were detected in year 1, 153 in year 2, 136 in year 3, and 118 in year 4. Prevalence of HAPI by year since the surveillance started was:
Year % (95%CI 7.4% - 9.4%)
Year % (95%CI 4.8% - 6.6%)
Year % (95%CI 4.0% - 5.6%)
Year % (95%CI 3.3% - 4.7%).
A step change was signaled and we used Maximum Likelihood Estimation to determine the timing of the step change occurred after July 2013 (year 2).[4] The monthly average rate of HAPI prevalence was 7.9% before the step change and an average rate of 4.5% thereafter (Figure 2) – a 43 % reduction in prevalence.
Table 1. Demographic characteristics of hospital census and audit sample populations on the day of audit.
Characteristic
Hospital census
N, (%)
Audit sample
Age (years)
0-14
15-29
30-44
45-59
60-74
75+
6356 (14.3)
(9.6)
5472 (12.3)
6909 (15.5)
9782 (22.0)
11773 (26.4)
2206 (19.6)
1003 (8.9)
1393 (12.4)
1657 (14.7)
2368 (21.1)
2620 (23.3)
Sex
Female
Male
22947 (51.5)
21600 (48.5)
5907 (525.5)
5340 (47.5)
Ethnicity
European
Maori
Pasifika
Asian
Other
Not known
27346 (61.4)
4871 (10.9)
6015 (13.5)
6093 (13.7)
153 (0.3)
69 (0.2)
6652 (59.1)
1266 (11.3)
1566 (13.9)
1629 (14.5)
51 (0.5)
83 (0.7)
Total
44,457
11,247
Method
We established a pressure injury surveillance programme in March 2012 to determine baseline prevalence, monitor the effect of improvement initiatives and to estimate annual prevalence. The full method is published elsewhere.[3]
We randomly sample from the midnight census 7 patients per unit (5 + 2 alternates) on the first Wednesday of every month. Audit forms with pre-populated patient data are automatically sent to each unit’s printer. 49 clinical units participate in the adult and children’s hospitals; delivery suites, emergency departments, and acute mental health are excluded. Data is collected on risk assessment, care planning, presence of pressure injury, and grade of injury (grades 1, 2, 3, & 4 - ungradable injuries are counted as grade 4 injuries).
All grade 1 pressure injuries are assumed to be hospital-acquired. All Grade 3 and 4 pressure injuries are verified as either hospital-acquired or present on admission to hospital. The unit of reporting is the patient and the most severe grade of pressure injury is reported for each patient, although data is collected on all pressure injuries present in each audited patient.
Improvement initiatives were developed during the first year of measurement and implemented in the following years thereafter.
Figure 1. Distribution of hospital-acquired pressure injuries by age at Auckland District Health Board hospitals.
Figure 1. Step change in prevalence of hospital-acquired pressure injuries at Auckland District Health Board
References
Baharestani MM, Black JM, Carville K, et al. Dilemmas in measuring and using pressure ulcer prevalence and incidence: an international consensus. Int Wound J 2009;6:
Gunningberg L, Dahm MF, Ehrenberg A. Accuracy of recording pressure ulcers and prevention after implementing an electronic health record in hospital care. Qual Safe Health Care 2008;17:281-5.
Jull A, McCall E, Chappell M, et al. Measuring hospital-acquired pressure injuries: a surveillance programme for monitoring performance improvement and estimating annual prevalence. Int J Nurs Studies 2016; 58:71-9.
Pignatiello JJ, Samuel TR. Identifying the time of a step change in the process fraction non-conforming. Qual Engineer 2001;13:
Monthly random audit is an excellent tool for monitoring hospital-acquired pressure injury prevalence. Annual whole-of-hospital surveys are unnecessary in large hospitals providing (1) random sampling is used and (2) an appropriate sample size is calculated. We now use the same audit as a vehicle for monitoring other patient safety initiatives.
Conclusion & Learnings