Table 2.
Cosinor parameters and model for subtypes of US requests.
| Outcome | Multivariate generalized regression estimates | Acrophase | Amplitude | |||||
|---|---|---|---|---|---|---|---|---|
| US requests | Cosine coefficient | (SE) | P | Sine coefficient | (SE) | P | (Month) | |
| US_Obstetrics | 0.064 | 0.023 | .005 | −0.149 | 0.035 | <.001 | November | 71.7 |
| US_Cranial | −0.166 | 0.068 | .323 | −0.341 | 0.170 | .045 | September | 2.67 |
| US_Doppler_lower_limbs | −0.219 | 0.068 | .001 | −0.305 | 0.068 | <.001 | September | 16.25 |
| US_Doppler in general | 0.354 | 0.137 | .009 | 0.125 | 0.135 | .353 | February | 4.08 |
| US_Doppler_upper_limbs | −0.163 | 0.163 | .317 | 0.358 | 0.165 | .030 | May | 2.98 |
| US_Neck | 0.107 | 0.079 | .168 | −0.379 | 0.078 | <.001 | October | 13.1 |
| US_Breast | 0.284 | 0.061 | <.001 | −0.745 | 0.065 | <.001 | October | 50.2 |
| Ultrasound_3D | −0.926 | 0.108 | <.001 | 0.300 | 0.098 | .003 | June | 25.5 |
| US_Pregnancy_fetal_anomaly | −0.485 | 0.350 | .165 | −0.316 | 0.344 | .358 | August | 1.08 |
| US_Anterior_Abdominal_Wall | 0.227 | 0.256 | .375 | 0.056 | 0.254 | .825 | February | 0.067 |
| US_Prostate | 0.188 | 0.050 | <.001 | 0.199 | 0.050 | <.001 | November | 20.6 |
| US_Soft_tissues | −0.182 | 0.238 | .444 | −1.13 | 0.274 | <.001 | October | 5.40 |
| US_Doppler_carotid | −0.374 | 0.235 | .112 | −0.501 | 0.239 | .035 | September | 2.57 |
| US_Doppler_testes | −0.023 | 0.165 | .885 | −0.197 | 0.166 | .237 | October | 1.32 |
| US_Legs | 0.322 | 0.385 | .402 | −0.771 | 0.408 | .059 | November | 1.38 |
| US_Urinary_tract | 0.041 | 0.423 | .921 | −1.18 | 0.495 | .016 | October | 1.78 |
| US_Hips | 0.632 | 30.73 | .090 | 0.472 | 0.365 | .196 | February | 1.47 |
| US_Pelvis_transvaginal | −0.404 | 0.326 | .214 | 0.061 | 0.319 | .848 | July | 0.81 |
| US_Gallbladder | −0.682 | 0.477 | .152 | −1.18 | 0.527 | .025 | September | 1.91 |
| US_Doppler_renal | −1.57 | 0.610 | .009 | −0.686 | 0.500 | .169 | August | 2.42 |
| US_Kidney | −0.857 | 0.430 | .045 | 0.135 | 0.395 | .732 | July | 1.35 |
| US_Pelvis | −0.079 | 0.068 | .244 | −0.164 | 0.068 | .016 | September | 7.17 |
| US_Adrenals | 0.048 | 0.365 | .893 | 0.048 | 0.365 | .893 | February | 0.09 |
| US_Axilla | 0.119 | 0.296 | .686 | −0.207 | 0.297 | .486 | November | 0.51 |
| US_Abdomen_and_pelvis | 0.116 | 0.020 | <.001 | −0.208 | 0.020 | <.001 | November | 106.1 |
| US_Abdomen_and_renal_tract | 0.141 | 0.031 | <.001 | −0.293 | 0.031 | <.001 | September | 66.1 |
| US_Testes | −0.063 | 0.066 | .336 | −0.057 | 0.066 | .383 | August | 3.39 |
| US_Abdomen | 0.162 | 0.019 | <.001 | 0.019 | 0.019 | .033 | January | 75.3 |
| US_Thyroid | −0.092 | 0.119 | .044 | −0.098 | 0.119 | .041 | September | 1.67 |
| US_Groin_and_inguinal_region | 0.161 | 0.168 | .033 | −0.378 | 0.171 | .002 | November | 2.93 |
Generalized linear regression coefficients (b), robust standard error (SE), and probability of significance (P) for cosine and sine transformations of the scan month. The models were adjusted for age and gender. The seasonality of US requests was inferred from the significance (P < .05) of the cosine and/or sine generalized linear regression coefficients.