Matching is a technique through which patients with and without an outcome of interest (in case-control studies) or patients with and without an exposure of interest (in cohort studies) are sampled from an underlying cohort to have the same or similar distributions of some characteristics. This technique is used to increase the statistical efficiency and cost efficiency of studies. In case-control studies, besides time in risk set sampling, controls are often matched for each case with respect to important confounding factors, such as age and sex, and covariates with a large number of values or levels, such as area of residence (e.g., post code) and clinics/hospitals. In the statistical analysis of matched case-control studies, fixed-effect models such as the Mantel-Haenszel odds ratio estimator and conditional logistic regression model are needed to stratify matched case-control sets and remove selection bias artificially introduced by sampling controls. In cohort studies, exact matching is used to increase study efficiency and remove or reduce confounding effects of matching factors. Propensity score matching is another matching method whereby patients with and without exposure are matched based on estimated propensity scores to receive exposure. If appropriately used, matching can improve study efficiency without introducing bias and could also present results that are more intuitive for clinicians.

BACKGROUND

Dobutamine is administered to patients with hypoperfusion associated with septic shock; however, its effect on mortality of septic shock remains unknown. We used a national inpatient database to investigate the effect of dobutamine on patients with septic shock.

METHODS

Adults with septic shock who received ≥30 mL/kg fluid and ≥10 μg/min noradrenaline and either vasopressin or adrenaline within 1 day after admission from 1 July 2010 to 31 March 2016 were identified by searching the Japanese Diagnosis Procedure Combination database. Stabilized inverse probability weighting analysis using propensity scores was performed to compare all-cause 28-day mortality and length of stay between patients who had and had not received dobutamine.

RESULTS

Of 4,747 eligible patients, 1,259 had received dobutamine and 3,488 had not. All-cause 28-day mortality did not differ significantly between the groups (risk difference, 0.1%; 95% confidence interval [CI], −3.3 to 3.4; P = 0.975). Receipt of dobutamine was significantly associated with longer hospital stay (difference, 3.8; 95% CI, 0.5–7.2; P = 0.024). Subgroup analysis showed that receipt of dobutamine was not significantly associated with length of stay in patients with cardiovascular disease (difference, −5.1 days; 95% CI, −11.7 to 1.5; P = 0.133), or those who received ≥20 μg/min noradrenaline (difference, 0.5 days; 95% CI, −6.8 to 7.7; P = 0.900).

CONCLUSIONS

Overall all-cause 28-day mortality in patients with septic shock did not significantly differ between patients who had and had not received dobutamine; however, receipt of dobutamine was significantly associated with longer hospital stay.

BACKGROUND

This study aimed to develop criteria for identifying patients with acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) from Japanese administrative data and validate the pre-existing criteria.

METHODS

This retrospective, multi-center validation study was conducted at eight institutes in Japan to verify the diagnostic accuracy of the disease name for AE-IPF. We used the Japanese Diagnosis Procedure Combination data to identify patients with a disease name that could meet the diagnostic criteria for AE-IPF, who were admitted to the eight institutes from January 2016 to February 2019. As a reference standard, two respiratory physicians performed a chart review to determine whether the patients had a disease that met the diagnostic criteria for AE-IPF. Furthermore, two radiologists interpreted the chest computed tomography findings of cases considered AE-IPF and confirmed the diagnosis. We calculated the positive predictive value (PPV) for each disease name and its combination.

RESULTS

We included 830 patients; among them, 216 were diagnosed with AE-IPF through the chart review. We combined the groups of disease names and yielded two criteria: the criteria with a high PPV (0.72 [95% confidence interval 0.62 to 0.81]) and that with a slightly less PPV (0.61 [0.53 to 0.68]) but more true positives. Pre-existing criteria showed a PPV of 0.40 (0.31 to 0.49).

CONCLUSION

The criteria derived in this study for identifying AE-IPF from Japanese administrative data show a fair PPV. Although these criteria should be carefully interpreted according to the target population, our findings could be utilized in future database studies on AE-IPF.