Flow diagram of the enrollment process.

We first identified 996,430 patients between 1 January 1996 and 31 December 2012 from the outpatient claim. We excluded patients who had some pre-existing diseases before the index date, had missed data, and could not match well for both cohorts. Finally, a total of 43294 patients with newly diagnosed headache other than migraine were identified as the non-migraine headache cohort. For each patient in the non-migraine headache cohort, 4 control patients were randomly selected, with frequency matching by age and sex.</p

Crude and adjusted hazard ratios for individual tinnitus, sensorineural hearing impairment, and sudden deafness.

Crude and adjusted hazard ratios for individual tinnitus, sensorineural hearing impairment, and sudden deafness.</p

The cumulative incidence of individual tinnitus, sensorineural hearing impairment, and sudden deafness.

The cumulative incidence of tinnitus (a), sensorineural hearing impairment (b), and sudden deafness (c) in the non-migraine headache cohort was significantly higher than that in the control cohort (log rank, p<0.001).</p

Crude and adjusted hazard ratios for combining tinnitus, sensorineural hearing impairment, and sudden deafness.

Crude and adjusted hazard ratios for combining tinnitus, sensorineural hearing impairment, and sudden deafness.</p

Characteristics in non-migraine headache and control cohorts in Taiwan, 1996–2012 (n = 216,470).

Characteristics in non-migraine headache and control cohorts in Taiwan, 1996–2012 (n = 216,470).</p

Hazard ratios for ischemic stroke occurrence according to predictive factors.

<p>Abbreviations: <b>HR</b>, hazard ratio; <b>95% CI</b>, 95% confidence interval; <b>vs</b>., versus;</p><p><b>CAD</b>, coronary artery disease; <b>COPD</b>, chronic obstructive pulmonary disease;</p><p><b>CHF</b>, congestive heart failure; <b>CKD</b>, chronic kidney disease; OP, surgery;</p><p><b>RT</b>, radiotherapy; <b>*</b>, <i>P</i><0.05; <b>**</b>, <i>P</i><0.01.</p><p><b>Note</b>: All <i>P</i> values were calculated by using Cox proportional hazard analysis.</p

Hazard ratios for stroke occurrence in lung cancer patients stratified by treatment groups and diabetes mellitus.

<p>Abbreviations: <b>HR</b>, hazard ratio; <b>95% CI</b>, 95% confidence interval; <b>RT</b>, radiotherapy.</p><p><b>Note 1</b>: All adjusted hazard ratios were estimated by using Cox proportional hazard analysis.</p><p><b>Note 2</b>: Patients in the surgery-alone group without diabetes were as the reference (value = 1).</p

Flow chart of patient allocation.

<p>With respect to patients treated with surgery plus radiotherapy (RT), patients treated with surgery alone were match-paired by using a ratio of 1∶4. <b>Note</b>: Data coded errors were validated by using the data subset of Registry for Catastrophe Illness.</p

Cumulative risk estimates of ischemic stroke occurrence according to diabetes and irradiation.

<p><b>Panel 3A</b>, adjusted HR in patients with type II diabetic mellitus (DM), 5.02 (95% CI 1.86–13.53; <i>P</i> = 0.001), when compared with those without type II DM; <b>Panel 3B</b>, adjusted HR in the surgery + RT group, 4.19 (95% CI 1.44–12.22; <i>P</i> = 0.009), when compared with the surgery alone group; and <b>Panel 3C</b>, the highest HR in patients with both DM and RT, 34.74 (95% CI 6.35–>100; <i>P</i><0.0001), when compared with patients with both of none (reference value = 1).</p

Patient and demographic characteristics according to treatment groups.

<p>Abbreviation: <b>RT</b>, radiotherapy; <b>CAD</b>, coronary artery disease.</p><p><b>Note 1</b>: All above factors were used for propensity-score match to balance study groups.</p><p><b>Note 2</b>: All <i>P</i> values were calculated by using chi-square test.</p