Improving screening in a Paediatric cohort for cystic fibrosis
related diabetes: a quality improvement project
To the Editor,
Screening for Cystic fibrosis (CF) related diabetes (CFRD) can be
difficult to achieve consistently. There are multiple guidelines
recommending oral glucose tolerance tests (OGTT) for
screening1,2. Furthermore, in the last decade CF
transmembrane receptor modulator therapy has become available, improving
the overall health of children and young people with CF, and potentially
reducing the need for regular screening.
Perth Children’s Hospital (PCH) is the only tertiary paediatric hospital
in Western Australia. All children and adolescents living with CF in
Western Australia and some parts of the Northern Territory are managed
at PCH. During the study the cohort included 206 patients, aged 0-18
years. 50% were on CFTR modulator therapy. Screening for CFRD was
mostly limited to annual glycosylated haemoglobin (HbA1C) and OGTT for
patients admitted to hospital for management of pulmonary exacerbations
of CF.
Here, we report a quality improvement project using the process of
‘Plan, Do, Study, Act’ (PDSA) cycles. Baseline assessment was performed
to define the current care provided at PCH. Prospective cycles were
analysed to assess improvement in screening. The aim of this study was
to improve screening for CFRD using OGTT to 50% by 2021. A secondary
aim was to characterise children at higher risk for a positive OGTT.
CFRD is different from type 1 and 2 diabetes mellitus and has
characteristics that can be seen in both type 1 and type 2 diabetes
including relative insulin deficiency and insulin resistance3,4. CFRD is more common with increasing age, in
females, and pancreatic exocrine insufficiency. The prevalence from the
Australian CF registry in 2019 in 12-17-year olds was 16% with impaired
glucose tolerance and 22% with CFRD5. CFRD can cause
poor growth and increase the risk of pulmonary exacerbations due to
hyperglycaemia promoting bacterial growth and increased thickness of
secretions4. Of note, a systematic review in
20196 showed no difference in Body Mass Index (BMI),
Forced Expiratory Volume in 1 second (FEV1) in patients
with CF and impaired glucose tolerance when compared to those with
normal glucose tolerance. Investigations to diagnosed diabetes include
HbA1c and OGTT. Neither of these tests are perfect. HbA1c reflects the
blood glucose levels over the past 2-3 months. The current recommended
level is based on type 2 diabetes when diabetic retinopathy becomes
prevalent. Also, HbA1c is often normal at the time of diagnosis of
CFRD4. For OGTT, the diagnostic cut offs for CFRD are
taken from type 2 diabetes and are designed to prevent microvascular
complications, not weight loss and loss of lung function.
The current recommendations from the Nutrition Guidelines for CF in
Australia and New Zealand, suggest that all children with CF aged 10
years and above have a yearly OGTT or earlier if
symptomatic2. Recommendations from Australian
Standards of Care for CFRD, state that yearly screening for glucose
tolerance should be performed in all patients with CF ≥ 10
years1. This can be done by either a formal OGTT or
random blood glucose testing if symptomatic.
At the start of 2019, there were 99 children and adolescents with CF 11
years and above being managed at PCH. 43/99 (43%) were males. 45/99
(45%) were prescribed CFTR modulator therapy. Four patients were
ineligible for screening.
To understand the problem in more detail an audit of all patients with
CF was performed. The following data were collected: age, sex, genotype,
eligibility for modulator therapy and if prescribed modulator,
pancreatic function, OGTT, HbA1c, weight and height, forced expiratory
volume in 1 second (FEV1), if admitted in 2019, and if
prescribed steroids for more than one month. Ethics approval was granted
through the low-risk pathway. Results were reviewed weekly and
statistical analysis was performed through Microsoft Excel (2022). We
identified 13/92 (14%) eligible patients had an OGTT in 2018. The known
prevalence of CFRD was 3/206 (1.4%) and impaired glucose tolerance was
2/92 (2%).
The implementation team consisted of a respiratory advanced trainee,
head of respiratory and sleep department and clinical lead for CF. A
series of PDSA cycles were conducted to improve screening. A range of
methods were used including data collection from electronic results
systems for baseline practice and post interventions. The implementation
team met post each strategy to discuss results and to plan the next
phase.
The cycles were as follows:
- PDSA cycle 1 – The aim was to improve screening of eligible
inpatients during 2019. At the start of every week an email was sent
to the inpatient team if there were inpatients eligible to be
screened.
- PDSA cycle 2 – The aim was to improve screening of the cohort over 10
years who had not had an OGTT since 2019. Letters were sent with forms
and information on OGTT to the families of eligible patients in June
2020. Each family was called fortnightly twice to discuss how they
planned to organise an OGTT. Results were reviewed weekly and reported
back to families.
- PDSA cycle 3 – The aim was to improve screening of cohort over 10
years who had not had an OGTT since 2020. The same information as
cycle 2 was sent to eligible families in August 2020. The next cycle
it was considered that a conservation in person may help improve
screening. Each patient was routinely seen in clinic every three
months.
- PDSA cycle 4 – The aim was to engage the wider team members and
communicate with patients and families in person. Each week clinical
staff were emailed with patients attending clinic that week with
outstanding screening. This was done for 3 months starting in
September 2020.
Over a two-year period four PDSA cycles were used to improve screening
for CFRD. See figure 1 for change in screening for CFRD. By the end of
2019, 23/38 (60%) of inpatients were screened, which was 24% of the
total population. Cycles 3 and 4 improved screening to 40% and 63%,
respectively. As a result of improved screening, 14/95 (15%) patients
were found to have glucose intolerance or CFRD. Patients with abnormal
OGTTs were pancreatic insufficient (90%), and prescribed modulator
therapy (70%). Their average BMI z score was -0.30 (standard deviation
1.3) and an average best FEV1 predicted of 88%
(standard deviation 15.6).