토의 및 결론

토의 및 결론은 다음과 같은 질문들에 대한 답을 제시해야 합니다.

연구 결과가 갖는 의미는 무엇인가?

다시 말해, 토의 및 결론에서는 연구 결과에 대한 해석을 제시해야 합니다. 이때 다음과 같은 점에 유의하시기 바랍니다:

  • 가장 중요한 것에서 덜 중요한 것의 순서로 기술합니다.
  • 자신의 연구 결과를 다른 사람들의 결과와 비교합니다: 결과가 일치하는지? 일치하지 않는다면, 차이를 발생시켰을 것으로 생각되는 이유들을 제시해야 함
  • 결론을 내릴 수 없는 결과들에 대해서도 가능한 한 최대한의 설명을 제공합니다. 이때 결과를 보다 분명히 할 수 있는 추가 연구들에 대한 의견을 제시하는 것도 좋은 방법입니다.
  • 연구가 갖는 한계를 간략하게 기술해 스스로도 연구의 부족한 점을 인식하고 있다는 것을 보여줍니다.
  • 해당 분야의 연구자들에게 연구 결과가 어떤 의미를 갖는지, 그리고 이 연구 결과가 응용될 경우 다른 분야의 연구자들에게, 또한 일반 대중들에게 어떤 의미를 갖는지 기술합니다.
  • 연구 결과가 앞선 연구들의 성과를 어떻게 확장시켰는지에 대해 기술합니다.
  • 연구 결과가 어떤 결론을 내리기에 충분하지 않은 예비적 성격을 띤다면, 후속 연구에 대한 제언을 덧붙입니다.
  • 토의 및 결론의 마지막 부분에 연구의 결론을 다시 한 번 명시합니다.

Example

Discussion

Feilong Wang, Wenzhi Pan, Shuming Pan, Shuyun Wang, Qinmin Ge and Junbo Ge Usefulness of N-terminal pro-brain natriuretic peptide and C-reactive protein to predict ICU mortality in unselected medical ICU patients: a prospective, observational study. Critical Care 2011;15(1):R42. Publisher full text

Methods

In this large scale study of 576 unselected medical ICU patients, we found that NT-proBNP and CRP independently predicted ICU mortality even after adjustment for the APACHE II score and multiple potential confounders including eGFR, age...

...In the present study, we also used a more sensitive test of improvement in model discrimination [27]. We found that the addition of NT-proBNP to the APACHE II score significantly increased the ability to predict ICU mortality as demonstrated by the IDI (6.6%, P = 0.003) and NRI (16.6%, P = 0.007) indices. NT-proBNP was not an independent predictor of ICU mortality in the non-cardiac subgroup after adjustment for APACHE II score and CRP. Kotanidou et al. [13] found that NT-proBNP predicted mortality independently after the adjusted APACHE II score and some inflammatory cytokines levels in non-cardiac ICU patients. But they used TNF-a, IL-6, and IL-10 rather than CRP and enrolled many surgical and multiple trauma cases. In the cardiac subgroup, NT-proBNP independently predicted ICU mortality while the AUC of the APACHE II score was not different from that of NT-proBNP (0.81 ± 0.03 vs 0.77 ± 0.04; P > 0.05). The addition of NT-proBNP to the APACHE-II score can obviously increase predictive ability (IDI = 10.2%, P = 0.018; NRI = 18.5%, P = 0.028). Therefore, although NT-proBNP could predict ICU mortality in unselected medical patents, it appeared to be more useful in cardiac patients than in non-cardiac patients.

...One previous study showed no predictive value of CRP for in-hospital mortality, even in univariate analysis [21]. The scope of the study was rather small (N = 103) and, thus, the statistical power was less than that of our study. Moreover, the endpoint of the previous study was in-hospital mortality but not ICU mortality. The present study revealed that CRP was also an independent predictor of ICU mortality in unselected patients or non-cardiac patients...

Several limitations of our study should be mentioned. First, neither echocardiography was performed nor cardiac function assessed in the present study. The division of subgroups was according to primary admission cause. Thus patients in the non-cardiac group may also have cardiac disease and cardiac dysfunction. However, patients with cardiac diseases as the primary principal diagnosis leading to ICU admission must have cardiac diseases. The statistical conclusion drawn from the cardiac group was appropriate. Second, this was a single-center study, and participants did not include surgery and trauma patients. The value for NT-proBNP in prediction of adverse outcome would be a bit different if the population was different. At last, a limitation of the net reclassification improvement and other reclassification measures is that they depend on the particular categories used [26]. We had used < 10%, 10% to 30%, and 30% to 50%, and > 50% for the risk of ICU death as risk categories. But there are still no well-recognized risk categories now. If the risk categories used had been different, the NRI would be a bit different.

Conclusions

In this large-scale study of unselected ICU patients, we confirmed that NT-proBNP and CRP can serve as moderate independent predictors of ICU mortality. Although the predictive ability was lower compared with the APACHE II score, but the addition of CRP or NT-proBNP or both to the APACHE II score could significantly improve the ability to predict ICU mortality, as demonstrated by IDI and NRI indices. NT-proBNP appeared to be more useful for predicting ICU outcomes in cardiac patients.

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