百日咳の診断・治療は、突き詰めればジレンマだらけとなる
早期治療のためには痙咳期前の典型的症状でない時点で治療しなきゃならないが、他疾患除外・診断正確性のために菌体検出が要求され治療タイミングが遅れやすい
成人においては、あまねく広まった「咳喘息」とやらの病名で誤診されている可能性がある。
せめて、吸気性笛音の存在がある症例では診断機会を逸しないようにしよう・・・
whoop
https://www.whoopingcough.net/introduction.
Clinically Diagnosing Pertussis-Associated Cough in Adults and Children: Chest Guideline and Expert Panel Report
Abigail Moore, et, al. FCCP On behalf of the CHEST Expert Cough Panel
DOI: https://doi.org/10.1016/j.chest.2018.09.027
https://journal.chestnet.org/article/S0012-3692(18)32575-3/fulltext
The American College of Chest Physicians (CHEST) methodologic guidelines and the Grading of Recommendations, Assessment, Development, and Evaluation framework were used. The Expert Cough Panel based their recommendations on findings from a systematic review that was recently published on the topic; final grading was reached by consensus according to Delphi methodology. The systematic review was carried out to answer the Key Clinical Question: In patients presenting with cough, how can we most accurately diagnose from clinical features alone those who have pertussis-associated cough as opposed to other causes of cough?
結果：事前設定メタ解析除外後、感度・特異度推定にて臨床的特徴4つのみ
- paroxysmal cough ：発作性咳嗽
- post-tussive vomiting ：咳き込み後嘔吐
- inspiratory whoop ：吸気性笛音
- absence of fever ：発熱なし
「発作性咳嗽」と「高熱なし」が感度高く (93.2% [CI, 83.2-97.4]、81.8% [CI, 72.2-88.7])、特異度低い (20.6% [CI, 14.7-28.1] 、18.8% [CI, 8.1-37.9])
「吸気性笛音」と「咳き込み後嘔吐」は感度低くy (32.5% [CI, 24.5-41.6] 、 29.8% [CI, 8.0-45.2])、特異度高い(77.7% [CI, 73.1-81.7] 、 79.5% [CI, 69.4-86.9])
小児においては、事前設定メタアナリシス除外後、感度特異度は小児(0-18歳)の臨床的い特性のみで形成され、「咳き込み後嘔吐」
小児の「咳き込み後嘔吐」が唯一、ほぼ感度高く (60.0% [CI, 40.3-77.0]) 、ほぼほぼ特異度高い (66.0% [CI, 52.5-77.3])
急性（3週間未満）咳嗽あるいは亜急性（3週間から8週間）咳嗽成人においては、「笛音」、「咳き込み後嘔吐」では、百日咳可能性としては"rule in"すべき事項であるが、一方、「発作性咳嗽」が無いこと、「発熱」の存在は"rule out"すべき事項
SUMMARY OF RECOMMENDATIONS:
1. For
adult patients complaining of acute cough (< 3 weeks in duration) or subacute cough (3-8 weeks), we suggest that clinicians should specifically assess for the
4 key characteristics of paroxysmal cough, post-tussive vomiting, inspiratory whooping, and absence of fever in ruling in or out a clinical diagnosis of pertussis. (Grade 2C)
Remark: Paroxysmal cough is defined as recurrent prolonged coughing episodes (i.e., an expiratory phase with multiple burst of outflow) with an inability to breathe during spells. Post-tussive vomiting is defined as vomiting induced by coughing. Inspiratory whooping is defined as a continuous inspiratory airway sound with a whooping quality to it. Fever is defined as any body temperature above the normal of 98.6oF(37oC).
2. For
adult patients complaining of acute or sub-acute cough, we suggest that clinicians consider that
the cough is unlikely to be due to pertussis if the patient has a fever or the cough is not paroxysmal in nature. (Grade 2C)
3. For
adult patients complaining of acute or subacute cough, we suggest that clinicians consider that the cough is likely to be caused by pertussis
if there is post-tussive vomiting or is associated with an inspiratory whooping sound. (Grade 2C)
4. For children complaining of acute cough (< 4 weeks duration), we suggest that clinicians should specifically assess for the 3 classical characteristics of paroxysmal cough, post-tussive vomiting, inspiratory whooping. (Ungraded consensus-based statement)
5. For children complaining of acute cough, we suggest that clinicians consider that the cough could be caused by pertussis if there is post-tussive vomiting. (Grade 2C)
6. For children complaining of acute cough, we suggest that clinicians consider that the cough could be caused by pertussis if there is paroxysmal cough or inspiratory whooping. (Ungraded consensus-based statement)
日本では遷延咳嗽というだけで、臨床的特徴を無視し、単回抗体値だけで、成人百日咳と診断してしまう集団がいるが、”精度の高い新検査法（百日咳菌LAMP法、2016年から健康保険適用、IASR 2017, 38: 33-34）”などで確認が必要となった昨今、この主張は消えるだろう。
全数届け出となった「百日咳」、疑い例を抽出することが一般医家にとっても重要となった。
https://www.mhlw.go.jp/file/05-Shingikai-10601000-Daijinkanboukouseikagakuka-Kouseikagakuka/shiryou3.pdf
百日咳 感染症法に基づく医師届出ガイドライン（初版）
平成 30 年4月25 日 国立感染症研究所
抜粋
診断方法：百日咳は発症日から検体採取までの時間経過と実施した検査の種類が結果に非常に大きく影響するため、検体採取日を含め、正確な情報収集が必要となる。※抗菌薬適正使用の観点から、臨床的に抗菌薬治療開始の判断材料となるのは、分離培養による百日咳菌の検出および病原体遺伝子の検出で、血清抗体価は判断材料とならない。
①分離同定による病原体の検出：検体の種類と採取日と結果を明記する。
②検体からの病原体遺伝子の検出：検体の種類と採取日と結果を明記する。検査方法については、LAMP法、PCR法のいずれかを確認し、明記する。
※PCR法陽性の場合、百日咳以外のパラ百日咳菌等の類縁菌による感染症の可能性がある
が、感染症法上の届出対象としてはBordetella pertussis感染症の場合のみである
従来の抗体法による診断では届け出対象とはならないようだ
”抗菌薬適正使用の観点”ってのがおかしくて、LAMP/PCR結果判明まで5−7日間かかるのが普通であり、治療windowを逃す可能性がある
Early treatment of pertussis is very important. The earlier a person, especially an infant, starts treatment the better. If a patient starts treatment for pertussis early in the course of illness, during the first 1 to 2 weeks before coughing paroxysms occur, symptoms may be lessened. Clinicians should strongly consider treating prior to test results if clinical history is strongly suggestive or patient is at risk for severe or complicated disease (e.g., infants). If a clinician diagnoses the patient late, antibiotics will not alter the course of the illness and, even without antibiotics, the patient should no longer be spreading pertussis.
タイミングを逃した抗菌薬は患者本人には役立たず、ただ単に、百日咳を広めないための治療となる
発作性咳嗽が生じるまでの期間が最も抗菌薬有効ってのと診断確実性の合間に臨床的ジレンマが生じる！
