Our study is the first to link AUDIT-C scores to risk of new-onset gastrointestinal illness, and the first to examine these associations in women. Men drinking in the hazardous range based on AUDIT-C scores of 5 or greater are at increased risk for hospitalization with a gastrointestinal diagnosis, new-onset liver disease, and/or new onset upper gastrointestinal bleed in the subsequent two years. Men with AUDIT-C scores of 9 or greater are at increased risk for all adverse gastrointestinal outcomes, including new-onset pancreatitis. Women drinking in the hazardous range based on AUDIT-C scores of 9 or greater are at increased risk for hospitalization with a gastrointestinal diagnosis in the subsequent two years.
Our findings support a growing literature that shows drinking alcohol in excess of recommended quantities and frequencies is linked to a variety of poor health outcomes. These data further establish the AUDIT-C as a useful scaled marker for alcohol-related risk. Like Au et al., we demonstrated that men with AUDIT-C scores of 5 or greater are at increased risk for hospitalization with a gastrointestinal illness.11
In addition, our findings show that AUDIT-C scores in men are linked to new-onset gastrointestinal disorders, and that women misusing alcohol are at risk as well. Unlike Au et al., we did not find differences in the associations of AUDIT-C scores and outcomes based on age. Under-ascertainment of gastrointestinal outcomes in younger groups in that study, which included Medicare data, and/or under-ascertainment in patients over 65 years old in the present study, may have biased outcomes.
As with studies linking AUDIT-C scores to risk of mortality,12
we found that non-drinkers are at increased risk for negative health outcomes compared to people drinking in the healthy range. This result may reflect the fact that patients with more medical co-morbidities are more likely to be non-drinkers. Our data show that patients in the AUDIT-C 0 group had the most comorbid illnesses and patients in the AUDIT-C 9–12 group had the fewest comorbidities. Many people may have stopped drinking due to health problems not related to alcohol, and some current non-drinkers are likely former problem drinkers. The increased risk of gastrointestinal disorders among abstainers might be due in part to alcohol-related harm from former heavy drinking.20
This may be especially true for women, who are more vulnerable to the toxic effects of alcohol.21,22
Indeed our data show that women in the AUDIT-C 0 group (abstainers) were at increased risk for new-onset liver disease.
With the exception of abstainers (AUDIT-C 0), women’s risk for adverse gastrointestinal outcomes increased only in women in the AUDIT-C 9–12 group. This is unexpected given that men had increased risk at lower scores (≥ 5), and women are more vulnerable than men, especially to the hepatotoxic effects of alcohol.21,22
Several factors may be biasing the results for women in the AUDIT-C 5–8 group to the null. First, even with a sample of over 9,000 women, we had low power to detect rare events (see Table ). Also, women typically underreport drinking levels compared to men due to increased stigma for heavy drinking.21,23
Thus, some women in the low level drinking group (AUDIT-C 1–4), may in fact have been drinking in the hazardous range.
These results need to be understood in light of several additional limitations. Misclassification and under-ascertainment of outcomes threaten the internal validity of this study. Outpatient ICD-9 codes are not as valid as inpatient codes.24
Many patients in the VHA system use Medicare and do not necessarily get transferred to VA hospitals, which likely decreases detected hospital admissions in the older age group.24
Incomplete or differential ascertainment of pre-existing gastrointestinal illness could have biased study results. The AUDIT-C assesses drinking in the past year but does not differentiate lifetime abstainers from previous high-risk or problem drinkers. Finally, AUDIT-C data collected in the course of a mailed survey of patient satisfaction may differ in important ways from screening data obtained in the course of clinical care.
The response rate for the SHEP survey was roughly 70% and responders differed from non-responders in age and gender. Although response bias may affect the generalizability of certain data reported here, such as the proportion of patients in various AUDIT-C groups, we have no reason to believe that estimates of the associations between the AUDIT-C and outcomes are affected by non-response.
These data from a large national sample of patients provide important new information about risks of new-onset gastrointestinal illness and related hospitalization associated with AUDIT-C scores. These data furthermore provide a platform for explicit alcohol-related advice, which has been shown to reduce alcohol use among hazardous drinkers.13,14
This study adds to the growing literature establishing the AUDIT-C as a ‘vital sign’ that might facilitate improved management of alcohol misuse.25