Locating the Seventh Cervical Spinous Process: Development and Validation of a Multivariate Model Using Palpation and Personal Information.

OBJECTIVE

The aim of this study was to develop and validate a multivariate prediction model, guided by palpation and personal information, for locating the seventh cervical spinous process (C7SP).

METHODS

A single-blinded, cross-sectional study at a primary to tertiary health care center was conducted for model development and temporal validation. One-hundred sixty participants were prospectively included for model development (n = 80) and time-split validation stages (n = 80). The C7SP was located using the thorax-rib static method (TRSM). Participants underwent chest radiography for assessment of the inner body structure located with TRSM and using radio-opaque markers placed over the skin. Age, sex, height, body mass, body mass index, and vertex-marker distance (D) were used to predict the distance from the C7SP to the vertex (D). Multivariate linear regression modeling, limits of agreement plot, histogram of residues, receiver operating characteristic curves, and confusion tables were analyzed.

RESULTS

The multivariate linear prediction model for D (in centimeters) was D = 0.986D + 0.018(mass) + 0.014(age) - 1.008. Receiver operating characteristic curves had better discrimination of D (area under the curve = 0.661; 95% confidence interval = 0.541-0.782; P = .015) than D (area under the curve = 0.480; 95% confidence interval = 0.345-0.614; P = .761), with respective cutoff points at 23.40 cm (sensitivity = 41%, specificity = 63%) and 24.75 cm (sensitivity = 69%, specificity = 52%). The C7SP was correctly located more often when using predicted D in the validation sample than when using the TRSM in the development sample: n = 53 (66%) vs n = 32 (40%), P < .001.

CONCLUSIONS

Better accuracy was obtained when locating the C7SP by use of a multivariate model that incorporates palpation and personal information.