= Solution
The supplementary excerpt uses \b[an adjusted <observational study> and a two-sample <Mendelian randomization> analysis].
The <observational study> examines co-occurrence of <hypercalcaemia> and <migraine> diagnoses in electronic health records, adjusting for age, sex, and ancestry. Its adjusted <odds ratio> is 1.58, with $P=4.75\times10^{-13}$.
The <two-sample Mendelian randomization> analysis combines the associations of eight <genetic variants> with <serum calcium> and with <migraine>, using a weighted <genetic risk score>. It estimates an <odds ratio> of 1.80 per genetically predicted 1 mg/dL higher <serum calcium>, with 95% <confidence interval> $(1.31,2.46)$. The <weighted-median Mendelian randomization estimator> and <MR-Egger regression> provide <sensitivity analyses>.
The measured and instrumented <exposure> is \b[<serum calcium>, rather than dietary <calcium intake> itself]. <Calcium intake> and <serum calcium> are not interchangeable interventions, and an <odds ratio> of 1.80 is an odds contrast rather than necessarily an 80% increase in probability. The shortened excerpt supplies two approaches; a further analysis in the full research paper is outside this excerpt.
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