Cost-Effectiveness

A recent theoretical analysis calculated that the cost per patient managed through syndromic diagnosis could be four times less than through clinical diagnosis (using the clinician's "best guess") and seven times less than etiologic diagnosis (using laboratory tests). Considering direct costs only, the cost per patient cured by syndromic management was estimated to be two to three times less than clinical diagnosis and three to four times less than etiologic diagnosis.¹⁵

The cost-effectiveness of a flowchart can be calculated in many different ways, but only the cost per patient will be discussed here. A relative estimate of these costs can be made without sophisticated calculation.

The cost per patient C is the cost incurred by the health structure in applying a flowchart to one patient. It is the sum of all the costs of diagnosis and treatment divided by the total number of patients for whom the flowchart is used.

Or:

C = (P_d × Diagnosis) + (P_t × Treatment)

Wherein P is a proportion, P_d is the proportion of patients who will undergo diagnosis (examinations, tests) and P_t is the proportion of patients who will be treated.

The following is a typical example of how to compare the cost-effectiveness of two different flowcharts. This same method can be used to compare a flow chart with an etiological approach to STD management.

For example, consider 200 men attending a health center seeking treatment for urethral discharge. Upon clinical examination, 180 of these men had urethral discharge. Of the 180 men with urethral discharge, 140 had a positive Gram stain.

According to flowchart A (not shown), treatment for gonorrhea and chlamydial infection is given to all patients with clinically confirmed urethral discharge. According to flowchart B (not shown), a Gram stain is performed. If intracellular gram-negative diplococci (IGND) are seen on the Gram stain, treatment will be given for both infections. If no IGND are seen, the patient will be treated only for chlamydial infection. The question is which of the two flowcharts is the cheapest.

The prices used in this exercise were: U.S. $0.10 for a physical examination (gloves, disinfectant), U.S. $0.30 for a Gram stain, U.S. $0.50 for Chlamydia infection treatment (doxycycline, seven days) and U.S. $2.50 for a treatment for gonorrhea (norfloxacin, one dose).

The cost per patient applying flowchart A would be:

C = (200/200 × U.S. $0.10) + (180/200 × U.S. $3.00) = U.S. $2.80

The cost per patient applying flowchart B would be:

Long-term costs will be determined in part by the cost of complications and sequelae, such as urethral stricture, chronic pain, extra-uterine pregnancies and infertility. These complications can be minimized by prompt and effective treatment. If a flowchart has a low sensitivity, missed or incorrectly treated infections will result. Treatment failure is also associated with the resistance pattern of the antibiotic used. Thus, the higher the sensitivity of the flowchart and the more effective the treatment, the lower the long-term costs will be. A balance must be reached between immediate costs, as reflected in the example above, and long-term costs.

Long-term costs also depend on days lost from work by STD patients and the number of additional people infected by someone with an STD, including secondary HIV infections. These long-term costs are very difficult to estimate.