There's been a push for “improved” coding in the last few years. Purported benefits include better accuracy in the medical record and improved quality of research that is drawn from administrative databases. The real effect of today's coding trends, as many of us already know on the ground, has been quite the opposite as illustrated in this recent study which looked at septic patients:
We assessed trends from 2005 to 2013 in the annual sensitivity and incidence of discharge ICD-9-CM codes for organ dysfunction (shock, respiratory failure, acute kidney failure, acidosis, hepatitis, coagulopathy, and thrombocytopenia) relative to standardized clinical criteria (use of vasopressors/inotropes, mechanical ventilation for greater than or equal to 2 consecutive days, rise in baseline creatinine, low pH, elevated transaminases or bilirubin, abnormal international normalized ratio or low fibrinogen, and decline in platelets)...
Acute organ dysfunction codes were present in 57,273 of 191,695 (29.9 %) hospitalizations with suspected infection, most commonly acute kidney failure (60.2 % of cases) and respiratory failure (28.9 %). The sensitivity of all organ dysfunction codes except thrombocytopenia increased significantly over time. This was most pronounced for acute kidney failure codes, which increased in sensitivity from 59.3 % in 2005 to 87.5 % in 2013 relative to a fixed definition for changes in creatinine (p = 0.019 for linear trend). Acute kidney failure codes were increasingly assigned to patients with smaller creatinine changes: the average peak creatinine change.. The mean number of dysfunctional organs in patients with suspected infection increased from 0.32 to 0.59 using discharge codes versus 0.69 to 0.79 using clinical criteria (p less than 0.001 for both trends and comparison of the two trends). The annual incidence of hospitalizations with suspected infection and any dysfunctional organ rose an average of 5.9 % per year (95 % CI 4.3, 7.4 %) using discharge codes versus only 1.1 % (95 % CI 0.1, 2.0 %) using clinical criteria.
Coding for acute organ dysfunction is becoming increasingly sensitive and the clinical threshold to code patients for certain kinds of organ dysfunction is decreasing. This accounts for much of the apparent rise in severe sepsis incidence and severity imputed from claims.
Among the motivations for this more aggressive coding are the potential for hospitals to get paid more under the prevailing crazy DRG scheme and improved public report cards for doctors, which are severity adjusted, based on codes.
The result is that research based on administrative databases is becoming increasingly suspect and public report cards are nearly meaningless. The consumer public doesn't know this but it probably doesn't matter given research that they largely ignore public reporting.