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Volume 11, Number 8—August 2005

Research

Optimizing Treatment of Antimicrobial-resistant Neisseria gonorrhoeae

Kakoli Roy*Comments to Author , Susan A. Wang*, and Martin I. Meltzer*
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Table 2

Input probabilities

Variable description Probabilities (%)
Base Range Distribution* Sources
Prevalence of gonorrhea in community among women 1.0 0–15 Triangular 2
Prevalence of ciprofloxacin-resistant Neisseria gonorrhoeae 0.1 0–20 Triangular 7
Prevalence of ceftriaxone-resistant N. gonorrhoeae 0 Assumed
Treatment failure when strain is resistant to antimicrobial agent 100 Assumed†
Treatment failure when strain is not resistant to antimicrobial agent 0 Assumed†
Infected with gonorrhea and symptomatic 30 20–50 Triangular 5,13,14
Infected with gonorrhea but without symptoms‡ 70 Residual‡ Calculated
Not infected but with gonorrhea symptoms 20 10–40 Triangular 5,13,15
Not infected and without gonorrhea symptoms‡ 80 Residual‡ Calculated
Recalled patient returning to clinic 40 20–80 Triangular 16,17
Sensitivity of nonculture-based tests 95 85–100 Triangular 14,18,19
Specificity of nonculture-based tests 97 95–99 Triangular 14,18,19
Sensitivity of culture-based tests 93 85–95 Triangular 14,18,19
Specificity of culture-based tests 97 95–97 Triangular 14,18,19
Concurrent HIV transmission§ 0.066 0–0.5 Triangular 20
Develop pelvic inflammatory disease (PID) and sequelae, among untreated gonorrhea cases 16 10–40 Triangular 5,13,14,21
Development of PID only (no sequelae)¶ 70 70–72 Uniform 15,16,21,22
Developing sequelae of PID¶
Infertility 6 1–6 Uniform 15,16,21
Ectopic pregnancy 8 5–9 Uniform 15,16,21
Chronic pelvic pain 16 15–20 Uniform 15,16,21
Urethritis 50 35–65 Uniform 15,16,21
Epididymitis 2 1–5 Uniform 15,16,21
For strategy 1, % of culture-positive samples tested for antimicrobial susceptibility# 80 Assumed
For strategy 3, % of culture-positive samples tested for antimicrobial resistance# 20 Assumed
Female-to-male transmission of gonorrhea§ 50 30–75 Uniform 5,13,23
Male-to-female transmission of gonorrhea§ 50 30–75 Uniform 5,13,23

*The probability distributions used in the Monte Carlo sensitivity analysis. Uniform distributions were constructed with the minimum and maximum of the given ranges. Triangular distributions were constructed with the minimum and maximum of the given ranges and the base case as the "most likely" value.
†Assumes 0% drug failure if organism is not resistant.
‡The probability of being infected and without gonorrhea symptoms is the residual value after considering the probability of being infected and with gonorrhea symptoms. Likewise, the probability of being not infected and without gonorrhea symptoms is the residual value after considering the probability of not being infected and with gonorrhea symptoms.
§Describes probability of initially infected woman transmitting disease to male partner, who then has the probability of infecting another female partner (or reinfecting original female partner after she has been cured of initial infection). Further, with the initial female-to-male transmission, the probability of concurrent HIV transmission exists.
¶Rate of PID (only) and rates of PID-related sequelae are given as percentages of those that develop PID.
#See Table 1 for descriptions of strategy 1 (ST1) and strategy 3 (ST3). In ST1, culture-positive samples are tested for ciprofloxacin resistance. In ST3, culture-positive samples are tested for ceftriaxone resistance.

Main Article

1In 2000, only 18% of gonorrhea tests performed by public health laboratories in the United States were culture-based tests.

2Monte Carlo simulation involves specifying a probability distribution of values for model inputs. A computer algorithm then runs the model for several iterations. During each iteration, the computer algorithm selects input values from the probability distributions, and calculates the output (e.g., cost per patient successfully treated). After the final run, the model provides results such as the mean, median, and 5th and 95th percentiles for each specified output.

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