HIV Laboratory Monitoring Identifies Persons Engaged in Care
HIV Laboratory Monitoring Identifies Persons Engaged in Care
We included in our analysis 10,321 VL and CD4 laboratory testing events for 2909 unique HOPS patients seen during 2010–2011. During the same period, a total of 20,928 medical encounters were recorded. The median duration between patients' first and last medical encounter was 14.5 months (interquartile range: 8.4–18.8, minimum: 0.0, maximum: 23.7). Of the 10,321 laboratory testing events, 519 were for CD4 measures alone, 1194 were for VL measures alone, and 8608 were events when both CD4 and VL were measured. The median time between a laboratory testing event and the nearest clinical visit was 0 days (interquartile range: 0–1.5); the median time varied by HOPS site from 0 to 6 days.
A total of 73.6% of laboratory testing events occurred on the same day as a medical encounter (see Figure S1, Supplemental Digital Content, http://links.lww.com/QAI/A585) and 89.3% of laboratory testing events occurred within the 3 weeks before or after a medical encounter. For 2148 (73.8%) patients, all laboratory testing events were classified as associated with a medical encounter (ie, occurred within 3 weeks before or after the medical encounter). The remaining 26.2% of patients with at least 1 HIV laboratory testing event performed outside the 3-week window (ie, classified as not associated with a medical encounter) were similar to patients who had each HIV laboratory testing event associated with a medical encounter in terms of age at index date, gender, education, disease stage, and HIV transmission risk group but were more likely to have been white non-Hispanic, to have been privately insured, to have been ART naive at index date, and to have been cared for at a private facility (Table 1).
In our sample, 88.2% of patients met criteria for being engaged in care using medical encounter data. Engagement in care by encounters ranged from 76.2% to 97.8% across participating HOPS sites. Using the proxy measure of care by laboratory monitoring, 77.3% of patients were engaged in care, ranging from 47.9% to 96.1% across participating HOPS sites. Using the proxy of engagement in care by laboratory monitoring to measure engagement in care by encounters had a sensitivity of 85.7%, a specificity of 86.0%, and positive and negative predictive values of 97.9% and 44.5%, respectively (Table 2). Overall, 14.2% of patients were misclassified. Three hundred sixty-six (12.6% overall, 88.4% of all misclassifications) patients were falsely classified as not engaged in care (falsely negative); that is, those patients were engaged in care by medical encounters but did not meet the definition of engagement in care by laboratory monitoring (see Figure S2, Supplemental Digital Content, http://links.lww.com/QAI/A585). Among the patients misclassified as not engaged in care by laboratory measures (22.7% overall), 55.5% (366/660) were actually engaged by encounters (Table 2). Only 48 (1.7%) patients were misclassified as falsely engaged in care; that is, they appeared engaged in care by laboratory monitoring but were not actually engaged according to medical encounters.
Patients who were misclassified as not engaged through the proxy laboratory measure but who were actually engaged through medical encounters (false negatives) were more likely to be younger, female, Hispanic, or non-Hispanic black race/ethnicity and to belong to the high-risk heterosexual transmission risk group compared with those who were correctly classified (Table 3). In contrast, participants who were misclassified as engaged in care through the proxy laboratory measure but who were actually not engaged through encounters (false positives) were more likely to be of non-Hispanic black or non-Hispanic white race/ethnicity compared with those correctly classified, although there were small numbers of false positives (N = 48) from which to ascertain patterns.
In bivariate analysis, younger age, non-Hispanic white race/ethnicity, receiving care in a private HOPS clinic, private insurance, and being ART naive at index date were associated with greater odds of having a laboratory test without a medical encounter (Table 4). When evaluated in a multivariate logistic generalized estimating equations model, receiving care in a private HOPS clinic and being ART naive at index date remained independently associated with having a laboratory testing event without an associated medical encounter (Table 4).
Results
Laboratory Testing Events and Medical Encounters
We included in our analysis 10,321 VL and CD4 laboratory testing events for 2909 unique HOPS patients seen during 2010–2011. During the same period, a total of 20,928 medical encounters were recorded. The median duration between patients' first and last medical encounter was 14.5 months (interquartile range: 8.4–18.8, minimum: 0.0, maximum: 23.7). Of the 10,321 laboratory testing events, 519 were for CD4 measures alone, 1194 were for VL measures alone, and 8608 were events when both CD4 and VL were measured. The median time between a laboratory testing event and the nearest clinical visit was 0 days (interquartile range: 0–1.5); the median time varied by HOPS site from 0 to 6 days.
A total of 73.6% of laboratory testing events occurred on the same day as a medical encounter (see Figure S1, Supplemental Digital Content, http://links.lww.com/QAI/A585) and 89.3% of laboratory testing events occurred within the 3 weeks before or after a medical encounter. For 2148 (73.8%) patients, all laboratory testing events were classified as associated with a medical encounter (ie, occurred within 3 weeks before or after the medical encounter). The remaining 26.2% of patients with at least 1 HIV laboratory testing event performed outside the 3-week window (ie, classified as not associated with a medical encounter) were similar to patients who had each HIV laboratory testing event associated with a medical encounter in terms of age at index date, gender, education, disease stage, and HIV transmission risk group but were more likely to have been white non-Hispanic, to have been privately insured, to have been ART naive at index date, and to have been cared for at a private facility (Table 1).
Laboratory Testing Events as a Proxy for Engagement in Care
In our sample, 88.2% of patients met criteria for being engaged in care using medical encounter data. Engagement in care by encounters ranged from 76.2% to 97.8% across participating HOPS sites. Using the proxy measure of care by laboratory monitoring, 77.3% of patients were engaged in care, ranging from 47.9% to 96.1% across participating HOPS sites. Using the proxy of engagement in care by laboratory monitoring to measure engagement in care by encounters had a sensitivity of 85.7%, a specificity of 86.0%, and positive and negative predictive values of 97.9% and 44.5%, respectively (Table 2). Overall, 14.2% of patients were misclassified. Three hundred sixty-six (12.6% overall, 88.4% of all misclassifications) patients were falsely classified as not engaged in care (falsely negative); that is, those patients were engaged in care by medical encounters but did not meet the definition of engagement in care by laboratory monitoring (see Figure S2, Supplemental Digital Content, http://links.lww.com/QAI/A585). Among the patients misclassified as not engaged in care by laboratory measures (22.7% overall), 55.5% (366/660) were actually engaged by encounters (Table 2). Only 48 (1.7%) patients were misclassified as falsely engaged in care; that is, they appeared engaged in care by laboratory monitoring but were not actually engaged according to medical encounters.
Patients who were misclassified as not engaged through the proxy laboratory measure but who were actually engaged through medical encounters (false negatives) were more likely to be younger, female, Hispanic, or non-Hispanic black race/ethnicity and to belong to the high-risk heterosexual transmission risk group compared with those who were correctly classified (Table 3). In contrast, participants who were misclassified as engaged in care through the proxy laboratory measure but who were actually not engaged through encounters (false positives) were more likely to be of non-Hispanic black or non-Hispanic white race/ethnicity compared with those correctly classified, although there were small numbers of false positives (N = 48) from which to ascertain patterns.
Odds of an HIV Laboratory Testing Event Being Unassociated With a Medical Encounter
In bivariate analysis, younger age, non-Hispanic white race/ethnicity, receiving care in a private HOPS clinic, private insurance, and being ART naive at index date were associated with greater odds of having a laboratory test without a medical encounter (Table 4). When evaluated in a multivariate logistic generalized estimating equations model, receiving care in a private HOPS clinic and being ART naive at index date remained independently associated with having a laboratory testing event without an associated medical encounter (Table 4).
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