Atraumatic Headache in US Emergency Departments
A total of 15 062 patient records of atraumatic headache-related ED visits were identified for our sample. This represents an estimated 54 million total ED visits (95% CI 49.8 to 58.1 million) by patients with atraumatic headache in the USA between 1998 and 2008, accounting for 4.5% (95% CI 4.3% to 4.6%) of all ED visits during this time period. Baseline demographic characteristics of this sample are summarised in Table 1. Relative to the non-headache ED population, visits for headache were overwhelmingly for patients aged 18–49 years (65.1% vs 47.0%, p<0.01). There is a greater representation of women overall in the atraumatic headache versus non-headache ED population but no significant differences on the basis of race or ethnicity (68.8% vs 53.0%, p<0.01).
Of the headache-related visits sampled, CT or MRI was ordered in approximately 11 million (95% CI 9.9 to 12.2 million) patients, representing 20.4% (95% CI 19.0% to 21.8%) of all ED visits for headache between 1998 and 2008. The mean age of patients who received imaging for atraumatic headache was 41.5 years (95% CI 40.6 to 42.5). Trends in CT/MRI utilisation and prevalence of ICP for ED visits with atraumatic headache over the past decade are shown in figure 1. Notably, the percentage of visits in which CT/MRI was ordered increased from 12.5% to 31% between 1998 and 2008 (p<0.01). This corresponded to a similar increase in CT/MRI utilisation across the same period among all ED visits in the survey, from 4.2% in 1998 to 15.0% in 2008 (p<0.01). Length of ED visit was 4.6 h (95% CI 4.4 to 4.8) among those who received CT/MRI compared with 2.7 h (95% CI 2.6 to 2.9) for those who did not (p<0.01).
(Enlarge Image)
Figure 1.
US trends in CT/MRI utilisation and yield of CT/MRI to diagnose severe intracranial pathology (ICP) in the emergency department (ED) evaluation of atraumatic headache, 1998–2008.
The observed trends in imaging utilisation remained consistent across several demographic variables including age, gender and race or ethnicity. The percentage of visits by men receiving CT/MRI increased from 13.9% to 35.6% between 1998 and 2008, while the percentage of visits by women increased from 11.8% to 29% (p<0.01 for both). A comparable and significant increase was seen among non-Hispanic white (11.8% to 30.5%), black (9.8% to 34.8%) and Hispanic (13.1% to 41.5%) individuals (p<0.01 for all). A significant increase in the use of imaging among adult patients from 18.9% to 44.9% in those aged ≥50 years and from 11.1% to 28.3% in those aged 18–49 years was also seen (p<0.01 for both).
In parallel with the observed increase in CT/MRI utilisation, the proportion of visits in which ICP was diagnosed by CT/MRI (ie, the yield to detect ICP) decreased from 10.1% to 3.5% between 1998 and 2008 (p<0.05, figure 1), with an average yield across the study period of 4.9% (95% CI 3.9% to 5.8%). Notably, the average yield to detect ICP was 10.4% (95% CI 7.8% to 13.1%) for patients aged ≥50 years but only 2.3% (95% CI 1.5% to 3.1%) for those aged <50 years in the study population (p<0.0001). No significant differences in yield were observed on the basis of race or ethnicity; however, a difference was noted based on the type of presenting headache complaint to the ED. The proportion of visits in which ICP was diagnosed among those with a non-migraine headache complaint who received imaging was 5.2% (95% CI 4.1% to 6.2%), while only three patient records in the survey sample across the study period with a reason for visit of migraine were associated with ICP upon imaging, representing a yield of 1.0% (95% CI 0% to 2.6%, N <30). The proportion of visits in which ICP was diagnosed among patients with private insurance who received imaging was 3.8% (95% CI 2.6% to 5.0%) compared with 6.6% (95% CI 4.5% to 8.7%) in those with Medicare, Medicaid or Worker's Compensation (p<0.01). Correspondingly, private insurance was associated with an increased likelihood of receiving CT/MRI (OR 1.25, 95% CI 1.1 to 1.4). Finally, 10 of the 18 variables examined were found to be associated with a significantly increased odds of ICP among the ED population with autraumatic headache (Table 2).
Results
A total of 15 062 patient records of atraumatic headache-related ED visits were identified for our sample. This represents an estimated 54 million total ED visits (95% CI 49.8 to 58.1 million) by patients with atraumatic headache in the USA between 1998 and 2008, accounting for 4.5% (95% CI 4.3% to 4.6%) of all ED visits during this time period. Baseline demographic characteristics of this sample are summarised in Table 1. Relative to the non-headache ED population, visits for headache were overwhelmingly for patients aged 18–49 years (65.1% vs 47.0%, p<0.01). There is a greater representation of women overall in the atraumatic headache versus non-headache ED population but no significant differences on the basis of race or ethnicity (68.8% vs 53.0%, p<0.01).
Of the headache-related visits sampled, CT or MRI was ordered in approximately 11 million (95% CI 9.9 to 12.2 million) patients, representing 20.4% (95% CI 19.0% to 21.8%) of all ED visits for headache between 1998 and 2008. The mean age of patients who received imaging for atraumatic headache was 41.5 years (95% CI 40.6 to 42.5). Trends in CT/MRI utilisation and prevalence of ICP for ED visits with atraumatic headache over the past decade are shown in figure 1. Notably, the percentage of visits in which CT/MRI was ordered increased from 12.5% to 31% between 1998 and 2008 (p<0.01). This corresponded to a similar increase in CT/MRI utilisation across the same period among all ED visits in the survey, from 4.2% in 1998 to 15.0% in 2008 (p<0.01). Length of ED visit was 4.6 h (95% CI 4.4 to 4.8) among those who received CT/MRI compared with 2.7 h (95% CI 2.6 to 2.9) for those who did not (p<0.01).
(Enlarge Image)
Figure 1.
US trends in CT/MRI utilisation and yield of CT/MRI to diagnose severe intracranial pathology (ICP) in the emergency department (ED) evaluation of atraumatic headache, 1998–2008.
The observed trends in imaging utilisation remained consistent across several demographic variables including age, gender and race or ethnicity. The percentage of visits by men receiving CT/MRI increased from 13.9% to 35.6% between 1998 and 2008, while the percentage of visits by women increased from 11.8% to 29% (p<0.01 for both). A comparable and significant increase was seen among non-Hispanic white (11.8% to 30.5%), black (9.8% to 34.8%) and Hispanic (13.1% to 41.5%) individuals (p<0.01 for all). A significant increase in the use of imaging among adult patients from 18.9% to 44.9% in those aged ≥50 years and from 11.1% to 28.3% in those aged 18–49 years was also seen (p<0.01 for both).
In parallel with the observed increase in CT/MRI utilisation, the proportion of visits in which ICP was diagnosed by CT/MRI (ie, the yield to detect ICP) decreased from 10.1% to 3.5% between 1998 and 2008 (p<0.05, figure 1), with an average yield across the study period of 4.9% (95% CI 3.9% to 5.8%). Notably, the average yield to detect ICP was 10.4% (95% CI 7.8% to 13.1%) for patients aged ≥50 years but only 2.3% (95% CI 1.5% to 3.1%) for those aged <50 years in the study population (p<0.0001). No significant differences in yield were observed on the basis of race or ethnicity; however, a difference was noted based on the type of presenting headache complaint to the ED. The proportion of visits in which ICP was diagnosed among those with a non-migraine headache complaint who received imaging was 5.2% (95% CI 4.1% to 6.2%), while only three patient records in the survey sample across the study period with a reason for visit of migraine were associated with ICP upon imaging, representing a yield of 1.0% (95% CI 0% to 2.6%, N <30). The proportion of visits in which ICP was diagnosed among patients with private insurance who received imaging was 3.8% (95% CI 2.6% to 5.0%) compared with 6.6% (95% CI 4.5% to 8.7%) in those with Medicare, Medicaid or Worker's Compensation (p<0.01). Correspondingly, private insurance was associated with an increased likelihood of receiving CT/MRI (OR 1.25, 95% CI 1.1 to 1.4). Finally, 10 of the 18 variables examined were found to be associated with a significantly increased odds of ICP among the ED population with autraumatic headache (Table 2).
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