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Zorluk: OrtaMeasures of Disease Frequency and Association

An international consortium of clinicians publishes the safety outcomes of a phase 3 clinical trial evaluating a novel Janus kinase (JAK) inhibitor for refractory rheumatoid arthritis. The study randomized patients equally into two arms: 2,0002,000 subjects received the active drug, while 2,0002,000 subjects received a placebo. During the 22-year observation window, severe opportunistic infections were documented in 160160 individuals taking the JAK inhibitor and in 6060 individuals taking the placebo.

Based on this data, what is the number of patients that need to be treated with the active drug to result in one additional severe opportunistic infection?

  1. A
    33
  2. B
    1313
  3. 2020Cevap
  4. D
    3333
  5. E
    4040

Cevap

The correct answer is 2020, which represents the Number Needed to Harm (NNH).
The Number Needed to Harm (NNH) is an epidemiological metric that represents the number of patients who need to be exposed to a risk factor (or treated with a drug) to cause one additional adverse event. It is calculated as the inverse of the Absolute Risk Increase (ARI). First, calculate the incidence of the adverse event in the exposed group (Iexposed=160/2,000=0.08I_{exposed} = 160 / 2,000 = 0.08). Next, calculate the incidence in the unexposed group (Iunexposed=60/2,000=0.03I_{unexposed} = 60 / 2,000 = 0.03). The ARI is the difference between these two incidences (0.08−0.03=0.050.08 - 0.03 = 0.05). Therefore, NNH=1/ARI=1/0.05=20NNH = 1 / ARI = 1 / 0.05 = 20.

Adım Adım Çözüm

1
Calculate the incidence of severe opportunistic infections in the exposed (JAK inhibitor) group.
160/2,000=0.08160 / 2,000 = 0.08 (or 8%8\%)
Determining the absolute risk in the exposed population is the first step to finding the risk increase.
2
Calculate the incidence of severe opportunistic infections in the unexposed (placebo) group.
60/2,000=0.0360 / 2,000 = 0.03 (or 3%3\%)
Determining the baseline risk is necessary to isolate the excess risk attributable solely to the drug.
3
Calculate the Absolute Risk Increase (ARI).
0.08−0.03=0.050.08 - 0.03 = 0.05 (or 5%5\%)
ARI represents the excess risk of the adverse event caused by the medication.
4
Calculate the Number Needed to Harm (NNH).
1/0.05=201 / 0.05 = 20
NNH is the inverse of the ARI and indicates the absolute number of patients who must be treated to cause one additional adverse event.

Anahtar Kavram

Number Needed to Harm (NNH) Calculation
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