Sensitivity of self-reported opioid use in case-control studies: Healthy individuals versus hospitalized patients

Abstract

BackgroundSeveral case-control studies have shown associations between the risk of different cancers and self-reported opium use. Inquiring into relatively sensitive issues, such as the history of drug use, is usually prone to information bias. However, in order to justify the findings of these types of studies, we have to quantify the level of such a negative bias. In current study, we aimed to evaluate sensitivity of self-reported opioid use and suggest suitable types of control groups for case-control studies on opioid use and the risk of cancer.MethodsIn order to compare the validity of the self-reported opioid use, we cross-validated the response of two groups of subjects 1) 178 hospitalized patients and 2) 186 healthy individuals with the results of their tests using urine rapid drug screen (URDS) and thin layer chromatography (TLC). The questioners were asked by trained interviewers to maximize the validity of responses; healthy individuals were selected from the companions of patients in hospitals.ResultsSelf-reported regular opioid use was 36.5% in hospitalized patients 19.3% in healthy individuals (p-value> 0.001).The reported frequencies of opioid use in the past 72 hours were 21.4% and 11.8% in hospitalized patients and healthy individuals respectively. Comparing their responses with the results of urine tests showed a sensitivity of 77% and 69% among hospitalized patients and healthy individuals for self-reports (p-value = 0.4). Having corrected based on the mentioned sensitivities; the frequency of opioid regular use was 47% and 28% in hospitalized patients and healthy individuals, respectively. Regular opioid use among hospitalized patients was significantly higher than in healthy individuals (p-value> 0.001).ConclusionOur findings showed that the level of opioid use under-reporting in hospitalized patients and healthy individuals was considerable but comparable. In addition, the frequency of regular opioid use among hospitalized patients was significantly higher than that in the general population. Altogether, it seems that, without corrections for these differences and biases, the results of many studies including case-control studies on opioid use might distort findings substantially.

Is Opium Use Associated with an Increased Risk of Lung Cancer? A Case-Control Study

“…In Kerman, a city in the south-east of Iran, the prevalence of O&D use has been estimated to be between 11% and 15% in the adult population (27,28). Recently, in a study conducted on hospital in-patients and their companions in Kerman, the prevalence of self-reported O&D use, was 36.5% in patients and 19.3% among their healthy companions (29) and this shows the high prevalence of O&D use in this region.…”

Opium Use Reporting Error in Case-Control Studies: Neighborhood Controls vs. Hospital Visitor Controls

“…According to the current study, visitor controls are recommended specially for case-control studies collecting biological samples, as they are more likely to provide biological samples, particularly urine samples, in the hospital setting-urine rapid test can be used to check opioid use during last 72 hours. Hospital controls can be selected among hospital visitors or hospitalized patients; the prevalence of opium use among the visitor controls is closer to the estimated prevalence of general population while prevalence of opium use is higher among disease controls [9,19,25]. Hence, using disease controls lead to non-differential misclassification (OR will be diluted towards the null value).…”

“…Hence, using disease controls lead to non-differential misclassification (OR will be diluted towards the null value). The higher prevalence of opium use among disease controls could be due to traditionally opioid use as a pain killer and various ailments, or, in fact, is because of long-term exposure to as the main risk factor for the reason of hospitalization [9].…”

“…Opium use was self-reported in both studies. In a previous validation study, we found a high level of sensitivity (77%) for self-reported opium use among visitor controls, using thin layer chromatography (TLC) as the gold standard [9]. Regular opium users defined as consuming opium at least once a week for at least a six-month consecutive period during the subjects' lifetime.…”

“…Despite many years of research, however, selection of appropriate controls remains a challenge [1][2][3][4][5][6], particularly when the exposure of interest is a sensitive question such as using a banned substance (e.g. Opium) [7][8][9][10].…”