PEDIATRICS Vol. 106 No. 2 August 2000, pp. 377-378

Cost-Effectiveness/Risk Factors

To the Editor.

Congratulations to Drs Benitz, Gould, and Druzin for their comprehensive review of the clinical risk factors for the acquisition of early-onset group B streptococcal sepsis (EOGBS),¹ the risk reduction attributable to various antibiotic intervention,² and the cost-effectiveness of various EOGBS prevention strategies.³ Their analysis is the most elegant to date, enhancing our understanding of efficient, cost-effective prevention of this often devastating disease.

Nevertheless, as we move increasingly toward a capitated payment schedule for obstetric and newborn services, I found it curious that the authors chose to analyze cost-effectiveness only in terms of "cost per case prevented." By so doing, the Centers for Disease Control and Prevention "risk factor" strategy appeared relatively inexpensive despite its alarmingly low effectiveness.

By measuring cost-effectiveness in terms of total program costs (prevention costs plus EOGBS disease costs) per 1000 pregnancies, one gains insight into both the cost of prevention and the cost of all of those EOGBS cases not prevented. In an effort to determine total program costs of each of the strategies delineated by Benitz et al, I recreated their model³ and used the following equation to determine total program costs:

Total program costs per 1000 pregnancies = (cost of test)(% tested)(1000) + (cost of intrapartum antibiotics)(% receiving intrapartum antibiotics)(1000) + (cost of neonatal antibiotics)(% receiving neonatal antibiotics)(1000) + (cost of EOGBS)(% of cases not prevented)(incidence rate per 1000 live births).

Using an EOGBS incidence rate of 3/1000 live births and $67 229 as the estimated cost per case of EOGBS,³ I found that the prevention strategy relying on the STREP B OIA had the lowest total program costs$57 813 per 1000 pregnancies versus $77 115 for the Centers for Disease Control and screening approach and $98,235 for the Prevention risk factor approach.

Because both the incidence and cost estimates may seem high to some, I then performed sensitivity analyses in which I varied the incidence of EOGBS from 1/1000 to 3/1000 live births and the cost per case of EOGBS from $15 200 to $67 229. The prevention strategy using the STREP B OIA had the lowest total program costs across the full range of incidences studied. The prevention strategy using the STREP B OIA had the lowest total program costs until the cost of EOGBS fell below $19 000 per case, at which point the risk factor approach had the lowest total program cost. Across all ranges, the strategy based on the STREP B OIA prevented the highest percentage of EOGBS cases.

As the American Academy of Pediatrics, American College of Obstetricians and Gynecologists, and Centers for Disease Control and Prevention begin to revise their 1996 guidelines for the prevention of EOGBS,⁴ I hope that they will consider this new data that Benitz et al have brought to light.

Kenneth H. Webb
BioStar, Inc.
Boulder, CO 80301

REFERENCES

1. Benitz WE, Gould JB, Druzin ML. Risk factors for early-onset group B streptococcal sepsis: estimation of odds ratios by critical literature review. Pediatrics. 1999;103(6). URL: http://www.pediatrics.org/cgi/content/full/103/6/e77
2. Benitz WE, Gould JB, Druzin ML. Antimicrobial prevention of early-onset group B streptococcal sepsis: Estimates of risk reduction based on critical literature review. Pediatrics. 1999;103(6). URL: http://www.pediatrics.org/cgi/content/full/103/6/e78
3. Benitz WE, Gould JB, Druzin ML. Preventing early-onset group B streptococcal sepsis: Strategy development using decision analysis. Pediatrics. 1999;103(6). URL: http://www.pediatrics.org/cgi/content/full/103/6/e76
4. Centers for Disease Control and Prevention. Prevention of perinatal group B streptococcal disease: a public health perspective. MMWR Morb Mortal Wkly Rep. 1996;45(No. RR-7):1-24

In Reply.

We appreciate Dr Webb's interest in our recent analyses related to prevention of early-onset group B streptococcal (EOGBS) infections. We chose not to include calculations of total costs related to GBS disease in our article for 2 reasons. First, it is quite difficult to obtain reliable estimates for the costs of caring for a case, because there is great variation in practice related to management of possible infection in newborn babies. The costs of new approaches to intrapartum management of at-risk pregnancies are difficult to predict, and could reflect increased or decreased utilization of antibiotics, diagnostic evaluations, or days of neonatal intensive care. Second, we do not believe that a net reduction in health care expenditures should be necessary to justify introduction of effective new treatments or preventive measures. Surely, a reduction in neonatal morbidity and mortality attributable to EOGBS infections has value to society, and would certainly justify an increase in expenditures if that were required.

However, we did perform preliminary calculations of total costs related to EOGBS disease. Although not included in the article because of the above considerations, the key conclusions of that analysis are consistent with those reached by Dr. Webb: 1) strategies that include screening for GBS colonization are substantially more effective than those based on risk factors alone, and 2) the costs of preventing a case of EOGBS disease using any of the strategies proposed over the last several years are substantially less than the costs of providing care for an infant with the disease.

William E. Benitz
Stanford University Medical Center
Lucile Salter Packard Children's Hospital at Stanford
Division of Neonatal and Developmental Medicine
Palo Alto, CA 94304-1510

Jeffrey B. Gould
Maurice L. Druzin