Methods
This was a retrospective study in which we collected the data of
children diagnosed with cystic fibrosis from January 2010 to December
2020 at All India Institute of Medical Sciences, New Delhi. An
institutional ethics committee approved this study. We included all
patients with cystic fibrosis age less than 18 years under follow-up
care of Pediatric chest clinic. We diagnosed CF by clinical phenotype
and two sweat chloride values of >60 mEq/L or identifying
two diseases causing mutations. Patients with incomplete data, precisely
the diagnostic test results and whose outcome was not known, were
excluded.
Data on demographic variables, clinical features, family history, type
of mutations, compliance to therapy, age of airway colonisation with
bacteria, lung function parameters, number of hospitalisations and
duration of hospitalisation were extracted on a pre-designed proforma.
Shwachman and Kulezycky (SK) severity scores were used to calculate and
grade the severity of illness (7).
Statistical analysis : We entered data in a Microsoft excel
sheet and exported it to Stata for analysis. Stata 15.0 [Stata Corp.,
College Station, TX] statistical software was used for data analysis.
Comparison of all variables was carried out between those who died and
survived. Continuous variables were compared using a t-test or
Mann-Whitney test as appropriate. We reported categorical data as
frequency (%) and compared using chi-square or fisher-exact test.
Kaplan Meier analysis followed by the log-rank test was used to analyse
the bivariable association of various potential factors with time to
death as an outcome. Subsequently, stepwise Cox regression analysis with
potential risk factors and time to death as the outcome was performed
with inclusion and exclusion criteria as p (0.05) and p (0.1),
respectively. In this study, a p-value of <0.05 was considered
statistically significant.