Prognosticating with the hospitalized-patient one-year mortality risk score using information abstracted from the medical record

We think that our study has several notable findings. First, we found that data abstracted from the medical record can be used to calculate the HOMR score to accurately predict individual death risk. The chart-HOMR score discriminated very well between patients who did and did not die (C statistic, 0.88), which extensively exceeds the discrimination of published death risk indices (whose C statistics range between 0.69 and 0.82). It is also possible that chart abstraction for the HOMR score—without functional status—is simpler than other indices since its components are primarily very objective. (Other indices for hospital-based patients required factors that could be difficult to abstract reliably from the medical record including meeting more than 1 guideline for noncancer hospice care⁹; ambulation difficulties¹⁰; scales such as the Exton-Smith Scale or the Short Portable Mental Status Questionnaire¹¹; weight loss¹²; functional status⁴; and pressure sore risk.¹³) Although expected risks for the chart-HOMR consistently underestimated observed risks (Figure 1), the mean deviation was small (with an absolute difference of 3.5% that can be used as a correction factor when determining expected risks with HOMR scores calculated from chart review), but it was an association between the chart-HOMR score and death risk that remained consistent through the cohort. Second, we found a small but significant decrease in the chart-HOMR score vs. the administrative-HOMR score (Figure 2). Some of these underestimates such as those for the number of ED visits or admissions by ambulance were expected since population-based health administrative databases would best capture such data. However, we were surprised that the comorbidity score was less when calculated using chart vs. database data (Figure 2). This finding is distinct from studies finding that particular comorbidities are documented in the chart are sometimes not coded.^14,15 However, we identified comorbidities in the administrative databases using a 1-year ‘look-back’ period so that diagnostic codes from multiple hospitalizations (and from multiple hospitals) could be used to calculate the Charlson Comorbidity Index for a particular patient; this has been shown to increase the capture of comorbidities.¹⁶ Third, we found that variables from the chart review indicating frailty were predictive of 1-year death risk independent of the chart-HOMR score (Table 2). This illustrates that mortality risk prediction can be improved for particular patient groups by adding new covariates to the HOMR. Further work is required to determine how to incorporate these (and possibly other) covariates into the HOMR to create a unique chart-HOMR score. Finally, we found that a geriatrics assessment in the ED was associated with a significant (and notable) decrease in death risk. With these data, we are unable to indicate whether this association is causative. However, these findings indicate that the influence of emergency geriatric assessments on patient survival needs to be explored in more detail.

Several issues about our study should be considered when interpreting its results. First, this was a single-center study and the generalizability of our results to other centers is unknown. However, our study had the largest sample size of all primary data prognostic index validation studies¹ ensuring that our results are, at the very least, internally reliable. In addition, our simple random sample ensured that we studied a broad assortment of patients to be certain that our results are representative of our institution. Second, we used a single abstractor for the study, which could limit the generalizability of our results. However, almost all the data points that were abstracted for our study were very objective.

In summary, our study shows that the HOMR score can be used to accurately predict 1-year death risk using data abstracted from the patient record. These findings will aid in individual patient prognostication for clinicians and researchers.

Disclosure

The authors report no financial conflicts of interest.