One-Year Uptake of Pneumococcal Conjugate Vaccine: A National Survey of Family Physicians and Pediatricians

Design

The study was a multistate, cross-sectional mail survey of pediatricians and family physicians who provide primary care to children ≤5 years of age. The study protocol was approved by the Institutional Review Boards of the University of Michigan Medical School and the Centers for Disease Control and Prevention (CDC).

Sample

Random samples of 788 family physicians and 833 pediatricians were drawn from the American Medical Association (AMA) Physician Masterfile by a contracted vendor (Medical Marketing Services). The Masterfile is the most comprehensive listing of physicians in the United States and contains both members and nonmembers of the AMA.

Sampling was conducted in 24 states, selected for their geographic diversity and vaccine financing strategy regarding PCV7, obtained from the National Immunization Program of CDC. States that have a “Vaccines for Children (VFC)-only” strategy (AR, CA, IN, MS, NJ, NV, PA, UT, VA, VT, WI, WV) purchase vaccine only for children who qualify for VFC (Medicaid beneficiaries, the uninsured, Native Alaskans and Native Americans, and underinsured children receiving vaccine at rural health clinics or federally qualified health centers). In states with “enhanced VFC” strategy (GA, MD, MI, MN, NY, OK, TX), the state purchases vaccine for VFC-eligible children as well as for underinsured children seen in private practice. In universal purchase states (ME, NC, NH, NM, WA), the state purchases vaccine for all children, regardless of insurance status. Sampling was conducted from each state proportional to physician representation in the Masterfile. Excluded from the sampling frame were physicians ≥70 years old and resident physicians.

Survey Instrument

Two separate survey instruments were designed: 1 for physicians who had adopted PCV7 recommendations for children <2 years old and 1 for physicians who had not. Several questions were common to both, allowing direct comparison of multiple physician characteristics and attitudes between adopters and nonadopters. Physicians’ specialty, gender, year of graduation from medical school, and board certification status were obtained from the AMA Masterfile.

Survey Administration

Before mailing, survey items were pilot-tested with family physicians and pediatricians. The survey was initially mailed with a personalized cover letter and a $3 incentive in April 2001. Nonrespondents were contacted with additional letters and surveys in May and June, 2001.

Data Analysis

All responses received by the study closure date of July 15, 2001, were included in the analysis. All analyses were conducted using SAS (version 6.12; SAS Institute, Cary, NC). Tests of significance in bivariate comparisons were computed using likelihood ratio χ2, except in cases of zero values in 1 or more cells, where Fisher’s exact test was used. Variables associated with adopting PCV7 in bivariate analyses were entered into 2 separate multivariate logistic regression models, based on the work of Cabana et al22 regarding barriers to physician adoption of practice guidelines. Model 1 compared the relative importance of variables characterizing physicians’ practice characteristics for adoption of PCV7. Model 2 compared variables representing physicians’ prior clinical experiences and attitudes that might influence their adoption of PCV7.

Characteristics of Respondents

Among 1621 physicians in the initial sample, 458 of 788 family physicians (FP) (58%) and 507 of 833 pediatricians (PD) (61%) responded, for an overall response rate of 60%. There were no significant differences between respondents and nonrespondents in gender, age, year of graduation from medical school, board certification, or state in which they practice. Some respondents were ineligible for analysis because they did not see children under age 5 years (157 FP, 53 PD), had retired (16 FP, 5 PD), or for other miscellaneous reasons, such as practice in the uniformed services or a suspended or revoked license (26 FP, 14 PD).

Our sample therefore contained 259 FP and 435 PD eligible for analysis. Of these physicians, 40% were women and 85% were board-certified in their clinical specialties. Although 26% graduated from medical school within the past 10 years, 11% graduated more than 30 years ago. Approximately 45% practice in states with a VFC-only strategy for PCV7 purchase, 44% in states with enhanced VFC financing, and 11% in states with universal purchase regarding PCV7. FP and PD respondents differed in several practice characteristics (Table 1).

Adoption of PCV7 Recommendations

At the time of the survey, 87% of respondents had adopted PCV7 recommendations for children <2 years old (68% FP and 99% PD; P < .001). The most common schedule used for administration of PCV7 was visits at 2, 4, 6, and >12 months of life (61%). Administration at 2, 4, 6, and 12 months of life was less common (34%), and a few physicians used a combination of visits at other months to administer PCV7 (5%).

Approximately 95% of physicians who administer PCV7 at the 2-, 4-, and 6-month visits reported that they administered ≥4 vaccine injections at the 2-month visit. In contrast, 93% of physicians who administer vaccines during extra visits gave ≤3 injections at the 2-month visit.

More than half (58%) of physicians who had adopted PCV7 said they had made no changes in their typical immunization schedule as a result of adding the vaccine. In contrast, 22% said that they now more often give combination hepatitis B/Haemophilus influenzae, type b vaccine, 14% said that they administer hepatitis B vaccine at birth and/or 1-month visits more frequently, and 12% reported that they now postpone either measles/mumps/rubella or the varicella vaccine until 15 months or later to give PCV7.

For older children aged 24 to 59 months, physicians who had adopted PCV7 differed in their approaches to recommending PCV7 for groups of children at increased risk for pneumococcal disease (Table 2). Almost all who administered PCV7 recommended the vaccine for immuno-compromised children, but there was substantial variation in patterns of physician recommendation regarding other high-risk categories. Physicians were significantly more likely to recommend PCV7 for children with recurrent otitis media and those in day care than for children of the same age who are not in a designated risk category. In contrast, overall physician recommendations for African American children were not significantly different from recommendations for standard-risk children.

Family Physician Factors Associated with Adoption of PCV7

Nearly all PD in this sample had adopted PCV7, so physician factors that distinguish PCV7 adopters (ADOP) from nonadopters (N-ADOP) are described only for FP respondents.

Practice characteristics of FP ADOP appear in Table 3. In general, FP who were in larger practices, cared for more newborns annually, and had practices with higher proportions of African American children and Medicaid beneficiaries were more likely to have adopted PCV7. In addition, female FP are more likely to have adopted PCV7 than male FP (78% vs 64%; P < .05). No differences were apparent among FP working in states with different vaccine financing strategies for PCV7 or in practices with different types of ownership or affiliation.

Attitudes and prior clinical experiences associated with physicians’ adoption of PCV7 fell into 3 categories: comfort with multiple injections at 1 visit, anticipated effectiveness of PCV7, and the influence of experiences with rotavirus vaccine. FP ADOP were more likely than N-ADOP to consider giving 4 or more vaccine injections at 1 visit (86% vs 35%; P < .001); 49% of N-ADOP said they would consider giving only 3 injections at a visit, and 16% administer 2 or fewer. ADOP were less likely to be concerned that multiple injections could cause adverse effects (26% vs 43%; P < .01). ADOP were also less likely to express their own concerns about too much pain with multiple injections (49% vs 78%; P < .001), and less likely to report parents’ concerns about multiple injections (65% vs 80%; P < .05). ADOP and N-ADOP were equally likely (49%) to be aware of nurses’ concerns about multiple injections.

Family physicians’ expectations about the effectiveness of PCV7 in preventing pneumococcal disease also distinguish ADOP from N-ADOP (Table 4). ADOP were significantly more likely to expect PCV7 to be effective against pneumococcal meningitis, pneumococcal sepsis, and otitis media. ADOP were also more likely than N-ADOP to have experienced a patient death or severe morbidity attributable to pneumococcal disease (30% vs 21%), although this finding only reached borderline statistical significance.

ADOP were significantly less likely to say that their experiences with rotavirus vaccine had influenced their approach to PCV7 (33% vs 46%; P < .05). Among physicians for whom rotavirus vaccine experiences had been influential, ADOP were more likely to say that they spend more time discussing vaccine risks with parents as a result (54% vs 19%; P < .001).

In separate multivariable logistic regression models, we compared the relative importance of several factors associated with the adoption of PCV7 by FP. The results of the models are shown in Table 5. Among practice characteristics, the number of newborns seen annually was the most influential factor predisposing to PCV7 adoption. Among physician attitudes and clinical experiences, the number of injections a physician would consider giving at a single visit was of greatest importance.

Deterrents to Physician Adoption of PCV7 Recommendations

Family physicians who had not adopted PCV7 at the time of this survey provided information about factors that were important in their decisions not to recommend this vaccine. Lack of insurance reimbursement for PCV7 was the most commonly cited factor (78%). Sixty-four percent of N-ADOP said that the vaccine purchase costs were too much for their practices to bear, and 62% said that they were concerned about possible adverse events related to the vaccine. Over half (56%) stated that they were unconvinced that a vaccine is necessary to combat pneumococcal disease; ie, they believed that antibiotics are sufficient to battle pneumococcal illness once it develops.