Comparison of different methods in estimating under reporting of injury cases in injury surveillance based on outpatient and emergency departments

Objective To understand the effects of different methods in estimating the underreporting rate of injury cases in injury surveillance based on outpatient and emergency departments and influencing factors,and provide evidence for the related research in future. Methods Four methods,capture-recapture with two independent simple random sampling, capture-recapture with one independent simple random sampling,sample based indirect estimation and sample based direct estimation,were used to estimate the underreporting rate of injury cases in hospitals under certain assumptions by conducting data simulation. The differences in point and interval estimation results of the 4 methods were compared. Results The first method had the worst point and interval estimation results and largest workload. The second method had better point and interval estimation results and less workload compared with the first method. The point and interval estimation results of the third method were better than those of the first method but worse than those of the second method,but the workload was least among four methods. The point and interval estimation results of the fourth method were very close to the results from the second method and it had less workload compare with the second method. Conclusion The use of capture-recapture methods had the requirement on the proportion of injury cases in outpatient and emergency departments. Increasing the number of outpatient and emergency cases from each random sampling,especially in the second random sampling,could enhance the precision of the estimated underreporting rate. Using sample based estimation,the introduction of sampling error could be reduced and the estimation precision could be improved compared with the estimation of total number of injury cases firstly. For each method,increasing the sample size could improve the precision of the estimated underreporting rate but add more workload. Based on the results,the fourth method is recommended to estimate the underreporting rate of injury cases in outpatient and emergency departments.