Is thrombocytopenia and postnatal weight gain associated with treatment-requiring retinopathy of prematurity? A matched case-control study.

PURPOSE
The purpose of the study was to investigate the association of platelet parameters and postnatal weight gain with treatment-requiring ROP (TR-ROP).


METHODS
In this retrospective matched case-control study, infants with TR-ROP were individually matched, according to gestational age and birth weight, with one or two untreated infants who developed no or spontaneously regressed ROP. Longitudinal data on platelet count (PLT), mean platelet volume (MPV), daily weight and platelet transfusions were collected. Platelet mass index (PMI) and weight standard deviation score (WSDS) were also calculated. Conditional logistic regression analysis was performed to adjust for matching.


RESULTS
Fourteen cases, presenting type I ROP, and 25 matched controls were included. The odds of developing TR-ROP decreased as PLT increased during 31st week of postmenstrual age (PMA) or during 1st and 2nd week of postnatal age (PNA). The odds of developing TR-ROP were 16.7 times higher in infants receiving at least one platelet transfusion compared with those who were not transfused. The odds of developing TR-ROP increased by 31.2% as the mean volume of platelet transfusion per infant increased by 1 ml. The odds of developing TR-ROP decreased as PMI increased during 1st week PNA, and as weight and WSDS increased during 4th -6th week PNA. Analysis of MPV, number of thrombopenic episodes per infant, number of platelet transfusions per infant and days with WSDS < -2 showed no association with TR-ROP.


CONCLUSION
To our knowledge, this is the first study ascertaining an association of platelet transfusions with type I ROP. Prospective cohort studies are required to confirm our findings.