“指征性混杂”在评估全科医疗中医疗质量对疾病结局影响方面的作用：一项病例对照研究的结果
The role of 'confounding by indication' in assessing the effect of quality of care on disease outcomes in general practice: results of a case-control study.
作者信息
de Koning Johan S, Klazinga Niek S, Koudstaal Peter J, Prins Ad, Borsboom Gerard J J M, Mackenbach Johan P
机构信息
Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, the Netherlands.
出版信息
BMC Health Serv Res. 2005 Jan 27;5(1):10. doi: 10.1186/1472-6963-5-10.
BACKGROUND
In quality of care research, limited information is found on the relationship between quality of care and disease outcomes. This case-control study was conducted with the aim to assess the effect of guideline adherence for stroke prevention on the occurrence of stroke in general practice. We report on the problems related to a variant of confounding by indication, that may be common in quality of care studies.
METHODS
Stroke patients (cases) and controls were recruited from the general practitioner's (GP) patient register, and an expert panel assessed the quality of care of cases and controls using guideline-based review criteria.
RESULTS
A total of 86 patients was assessed. Compared to patients without shortcomings in preventive care, patients who received sub-optimal care appeared to have a lower risk of experiencing a stroke (OR 0.60; 95% CI 0.24 to 1.53). This result was partly explained by the presence of risk factors (6.1 per cases, 4.4 per control), as reflected by the finding that the OR came much closer to 1.00 after adjustment for the number of risk factors (OR 0.82; 95% CI 0.29 to 2.30). Patients with more risk factors for stroke had a lower risk of sub-optimal care (OR for the number of risk factors present 0.76; 95% CI 0.61 to 0.94). This finding represents a variant of 'confounding by indication', which could not be fully adjusted for due to incomplete information on risk factors for stroke.
CONCLUSIONS
At present, inaccurate recording of patient and risk factor information by GPs seriously limits the potential use of a case-control method to assess the effect of guideline adherence on disease outcome in general practice. We conclude that studies on the effect of quality of care on disease outcomes, like other observational studies of intended treatment effect, should be designed and performed such that confounding by indication is minimized.
背景
在医疗质量研究中，关于医疗质量与疾病结局之间关系的信息有限。本病例对照研究旨在评估在全科医疗中遵循卒中预防指南对卒中发生的影响。我们报告了与一种指示性混杂变体相关的问题，这在医疗质量研究中可能很常见。
方法
从全科医生（GP）的患者登记册中招募卒中患者（病例）和对照，一个专家小组使用基于指南的审查标准评估病例和对照的医疗质量。
结果
共评估了86例患者。与预防保健无缺陷的患者相比，接受次优护理的患者发生卒中的风险似乎更低（比值比[OR]0.60；95%置信区间[CI]0.24至1.53）。这一结果部分可由风险因素的存在来解释（病例组每例有6.1个，对照组每例有4.4个），这一发现反映在对风险因素数量进行调整后，OR更接近1.00（OR 0.82；95%CI 0.29至2.30）。卒中风险因素较多的患者接受次优护理的风险较低（存在的风险因素数量的OR为0.76；95%CI 0.61至0.94）。这一发现代表了“指示性混杂”的一种变体，由于关于卒中风险因素的信息不完整，无法对其进行完全调整。
结论
目前，全科医生对患者和风险因素信息的记录不准确，严重限制了病例对照方法在评估全科医疗中遵循指南对疾病结局影响方面的潜在用途。我们得出结论，关于医疗质量对疾病结局影响的研究，与其他预期治疗效果的观察性研究一样，在设计和实施时应尽量减少指示性混杂。
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