Photogrammetry: an accurate and reliable tool to detect thoracic musculoskeletal abnormalities in preterm infants.

Objective: To analyse the accuracy and reproducibility of photogrammetry in detecting thoracic abnormalities in infants born prematurely.

Design: Cross-sectional study.

Setting: The Premature Clinic at the Federal University of São Paolo.

Participants: Fifty-eight infants born prematurely in their first year of life.

Outcome Measures: Measurement of the manubrium/acromion/trapezius angle (degrees) and the deepest thoracic retraction (cm). Digitised photographs were analysed by two blinded physiotherapists using a computer program (SAPO; http://SAPO.incubadora.fapesp.br) to detect shoulder elevation and thoracic retraction. Physical examinations performed independently by two physiotherapists were used to assess the accuracy of the new tool.

Results: Thoracic alterations were detected in 39 (67%) and in 40 (69%) infants by Physiotherapists 1 and 2, respectively (kappa coefficient=0.80). Using a receiver operating characteristic curve, measurement of the manubrium/acromion/trapezius angle and the deepest thoracic retraction indicated accuracy of 0.79 and 0.91, respectively. For measurement of the manubrium/acromion/trapezius angle, the Bland and Altman limits of agreement were -6.22 to 7.22° [mean difference (d)=0.5] for repeated measures by one physiotherapist, and -5.29 to 5.79° (d=0.75) between two physiotherapists. For thoracic retraction, the intra-rater limits of agreement were -0.14 to 0.18cm (d=0.02) and the inter-rater limits of agreement were -0.20 to -0.17cm (d=0.02).

Conclusion: SAPO provided an accurate and reliable tool for the detection of thoracic abnormalities in preterm infants.