When general practitioners don't feel appreciated by their patients: prospective effects on well-being and work-family conflict in a Swiss longitudinal study.

BACKGROUND: Impaired well-being and high work-family conflict are critical issues among GPs. This research examined an understudied psychosocial risk factor for these outcomes, namely GPs' perception that they invest more in the relationship with their patients than what they receive in return (i.e. lack of reward in their relationship with patients). OBJECTIVE: To test the effect of lack of reward as a risk factor for poor well-being and work-family conflict among GPs. METHODS: Longitudinal study (12 months time lag). 272 GPs in Switzerland [mean age 54.5 (SD = 8.3), 73% male] volunteered to participate in the study. 270 participants completed the baseline survey and 252 completed the follow-up survey. Of these, six retired between the baseline and the follow-up survey, resulting in a sample size of 246 participants at t2. Outcome measures were burnout, sleep problems, self-perceived health and work-family conflict. RESULTS: Strength and direction of prospective effects were tested using cross-lagged models. Lack of reward was related to an increase in emotional exhaustion (ß = 0.15), sleep problems (ß = 0.16) and work-family conflict (ß = 0.19) and a decrease in self-perceived health (ß = -0.17). Effects on depersonalization and personal accomplishment were not significant. Regarding reversed effects of impaired well-being on lack of reward, emotional exhaustion (ß = 0.14) and self-perceived health (ß = -0.13) predicted future level of lack of reward. CONCLUSION: Lack of reward by patients is a risk factor in GPs' mental health.

[Teaching practice recommendations: prevention and screening]. / Enseignement de recommandations pour la pratique: la prévention et le dépistage.

The aim of this article is to provide guidance to family doctors on how to tutor students about effective screening and primary prevention. Family doctors know their patients and adapt national and international guidelines to their specific context, risk profile, sex and age as well as to the prevalence of the disorders under consideration. Three cases are presented to illustrate guideline use according to the level of evidence (for a 19-year-old man, a 60-year-old woman, and an 80-year-old man). A particular strength of family medicine is that doctors see their patients over the years. Thus they can progressively go through the various prevention strategies, screening, counselling and immunisation, accompanying their patients with precious advice for their health throughout their lifetime.

[Pre travel advice - a study among Swiss general practitioners]. / Beratung vor der Reise - eine Umfrage bei Schweizer Hausärzten.

Up to 65 % of travellers seek pre-travel advice at their general practitioner. Professionals should inform about the most common and most dangerous health threats, requiring up-to-date knowledge about epidemiology of respective disorders. The aim of the present study was to investigate the content of pre-travel advice given by general practitioners in order to provide them with better expert support from travel medicine specialists. One third of them perform pre-travel advice weekly, and some two thirds do so at least monthly. The most frequently discussed topics are malaria, immunisation, insect bite prevention and travellers' diarrhoea. Less than half of the advice sessions included talking about the risk of accidents. Apart from the need for yellow fever vaccination, referral to travel medicine experts was highest for immunocompromised and pregnant travellers, and for trips to "high risk" countries. A considerable number of practitioners do not comply with the Swiss recommendations, continuously updated in the Bulletin of the Federal Office of Public Health, possibly because only 21 % consult them at regular intervals.

Enhanced didactic methods of smoking cessation training for medical students--a randomized study.

BACKGROUND: It is essential that medical students are adequately trained in smoking cessation. A web-based tobacco abstinence training program might supplement or replace traditional didactic methods. METHODS: One-hundred and forty third-year medical students were all provided access to a self-directed web-based learning module on smoking cessation. Thereafter, they were randomly allocated to attend 1 of 4 education approaches: (a) web-based training using the same tool, (b) lecture, (c) role playing, and (d) supervised interaction with real patients. RESULTS: Success of the intervention was measured in an objective structured clinical examination. Scores were highest in Group 4 (35.9 ± 8.7), followed by Groups 3 (35.7 ± 6.5), 2 (33.5 ± 9.4), and 1 (28.0 ± 9.6; p = .007). Students in Groups 4 (60.7%) and 3 (57.7%) achieved adequate counseling skills more frequently than those in Groups 2 (34.8%) and 1 (30%; p = .043). There was no difference in the scores reflecting theoretical knowledge (p = .439). Self-assessment of cessation skills and students' satisfaction with training was significantly better in Groups 3 and 4 as compared with 1 and 2 (p < .001 and p = .006, respectively). CONCLUSIONS: Role playing and interaction with real patients are equally efficient and both more powerful learning tools than web-based learning with or without a lecture.

[High-quality hospital discharge summaries - general practitioners expectations]. / Welche Anforderungen stellt der Hausarzt an einen guten Spitalaustrittsbericht?

Hospital discharge summaries ensure treatment continuity after hospital discharge. In Switzerland discharge letters are a celebrated custom and a tool for training young colleagues. The primary purpose is to guarantee high-quality care of patients treated by hospital staff and general practitioners. From the perspective of the patient's general practitioner discharge summaries should convey current and accurate medically important patient data to the physician responsible for follow-up care. In the era of highly developed electronic data transfer and introduction of diagnose related groups (DRGs), it will be necessary to transmit hospital discharge information selectively to different target groups. Nevertheless data protection and medical secret must be complied with.

[Hypertension in general practice in Switzerland]. / L'hypertension artérielle au cabinet du médecin de famille en Suisse.

Arterial hypertension is a leading problem in general practice. Nevertheless, reliable epidemiological and outcome data on hypertensive patients obtained directly from GPs are scarce. We report some results of our GP cohort "HccHs" of the Institute of general practice Basel. Swiss GPs fill in relevant baseline and follow-up data of their own hypertensive patients in an internnn based questionnaire The first results show a good blood pressure control. 94% of 950 patients receive antihypertensive drug treatment. 24-hour-blood pressure-measurement is helpful for baseline diagnosis and in drug treated hypertensive patients. 24-hour-blood pressure-measurement identifies patients with elevated office but normal 24-hour blood pressure with good prognosis.

Effect of guideline revisions by the Swiss Society of Hypertension on blood pressure control in hypertensive patients from primary care.

  BACKGROUND: Recommendations for blood pressure goals have considerably changed across time, in particular for high-risk patients with diabetes mellitus and/or renal dysfunction. Before 2009, Swiss Society of Hypertension (SSH) guidelines recommended lowering blood pressure to <135/85 mm Hg and after 2009 to <130/80 mm Hg in high-risk patients. It remains unclear whether guideline changes for blood pressure targets are associated with reductions in blood pressure in hypertensive patients treated in primary care. The objective was to report the association between guideline change and blood pressure target achievement, as well as the prevalence of blood pressure target achievement according to guidelines and to identify factors associated with blood pressure target achievement in a Swiss primary care sample of treated hypertensive patients. METHODS: We used longitudinal data from the Swiss Hypertension Cohort Study, which was a prospective, observational study conducted by the Centre for Primary Health Care of the University of Basel from 2006 to 2013. General practitioners (GPs) enrolled 1003 patients attending their practice with a pre-existing diagnosis of arterial hypertension or office blood pressure measurement ≥140/90 mm Hg and assessed office blood pressure, cardiovascular risk factors, subclinical organ damage, diabetes mellitus, and established cardiovascular and renal disease. Mixed-effects regression models were used to estimate the associations of (1) the change in hypertension guidelines in 2009 with blood pressure and antihypertensive therapy in high-risk patients, and (2) cardiovascular risk factors with blood pressure target achievement in patients with complicated and uncomplicated hypertension. Models were adjusted for sociodemographic and health-related covariates. Missing data were imputed using a “multiple imputation by chained equation” approach. RESULTS: At baseline, hypertensive patients were on average 65.9 ± 12.5 years old and 55% were male. Blood pressure targets were achieved in 47% of patients with uncomplicated hypertension and in 13% of high-risk patients at baseline. In multivariable analyses adjusted for potential confounding factors, a visit by high-risk patients after 2009 was associated with decreased systolic office blood pressure (−5.40 mm Hg, 95% confidence interval [CI] −8.08 to 2.73) and a trend towards an increased use of pharmacological combination therapy (odds ratio [OR] 1.85, 95% CI 0.94 to 3.63; p = 0.073) compared with a visit before 2009. Neither a reduction of diastolic blood pressure nor an increase of blood pressure target achievement in high-risk patients was observed after 2009. High-risk patients were slightly more likely to achieve blood pressure targets at later follow-up visits than at baseline (OR 1.35, 95% CI 0.98 to 1.86; p = 0.068). In patients with uncomplicated hypertension, factors associated with the likelihood to achieve blood pressure goals were the increased use of pharmacological combination therapy (OR 1.19 per combination increase: e.g., dual therapy vs monotherapy, 95% CI 1.02 to 1.40), left ventricular hypertrophy (OR 0.58, 95% CI 0.36 to 0.93), older age (OR 1.19 per 10 years, 95% CI 1.02 to 1.40) and the number of follow-up examinations (OR 1.44 per follow-up visit, 95% CI 1.21 to 1.72). CONCLUSION: Overall, blood pressure goal attainment remains low for treated hypertensive patients followed up by primary care physicians in Switzerland. Independent of known confounding factors for blood pressure, the 2009 guideline change in high-risk patients was associated with a reduction in systolic office blood pressure together with an increase in pharmacological combination therapy. These results highlight primary care physicians’ efforts to implement blood pressure guidelines. Further, blood pressure goal attainment was more likely to be achieved in later follow-up visits, indicating that it takes time and regular follow-up visits with the GP to meet blood pressure goals.  .

One-on-one long-term tutorials in general practitioners' practices - a successful new teaching concept in primary care medicine.

To improve teaching in practical and communicative skills and knowledge in day-to-day medical practice, in 1997 we introduced one-on-one tutorials in general practitioners' offices as a mandatory part of medical students' academic education. Students participate actively half a day per week in their 3rd and 4th academic years (out of 6) in the office or clinic of a trained personal tutor. We recruited 270 general practitioners in town or from surrounding rural areas for this purpose. 85% of students choose general practitioners as their tutors and 15 % tutors in hospitals. To test whether the tutorials' aims were achieved, in 2005 we performed a detailed questionnaire evaluation after seven years' experience of one-on-one tutorials. All 236 students involved were asked to participate. The response rate was almost complete (98%). 233 anonymous questionnaires were analysed. Students reported improvement in knowledge, social and communicative skills and personal motivation. The overall rating of the one-on-one tutorials obtained 5.3 on a 6 point scale and achieved the top ranking among all university medical faculty classes. In-practice long-term one-on-one medical student-general practitioner tutorials can be recommended for implementation.

Cardiovascular risk stratification in primary care patients with arterial hypertension: Results from the Swiss Hypertension Cohort Study (HccH).

AIMS: Few data are available on cardiovascular risk stratification in primary care patients treated for arterial hypertension. This study aimed at evaluating the cardiovascular risk profile of hypertensive patients included into the Swiss Hypertension Cohort Study according to the 2013 European Society of Hypertension/European Society of Cardiology Guidelines. METHODS: The Swiss Hypertension Cohort Study is a prospective, observational study conducted by the Centre for Primary Health Care of the University of Basel from 2006 to 2013. Patients with a diagnosis of arterial hypertension (office blood pressure measurement ≥140/90 mmHg) were enrolled. Office blood pressure measurement, cardiovascular risk factors, subclinical organ damage, diabetes mellitus, and established cardiovascular and renal disease were recorded at baseline and at an annual interval during routine consultations by general practitioners in Switzerland. RESULTS: In total, 1003 patients were eligible for analysis (55.6% male, mean age: 64.0 ± 13.2 years). At baseline, 78.5% of patients presented with either more than three additional cardiovascular risk factors, diabetes mellitus or subclinical organ damage, while 44.4% of patients had a high or very high overall cardiovascular risk. Cardiovascular risk factors and information about diabetes mellitus, established cardiovascular disease and renal disease were recorded mostly completely, whereas substantial gaps were revealed regarding the assessment of subclinical organ damage. CONCLUSION: The present findings demonstrate that the majority of primary care patients with arterial hypertension bear a substantial number of additional cardiovascular risk factors, subclinical and/or established organ damage. This emphasizes the need for continuous cardiovascular risk stratification and adequate treatment of arterial hypertension in Switzerland.

Physicians' ability to predict patients' adherence to antihypertensive medication in primary care.

Addressing adherence to medication is essential and notoriously difficult. The purpose of this study was to determine physicians' ability to predict patients' adherence to antihypertensive therapy. Primary care physicians were asked to predict the adherence to medication of their hypertensive patients (n=42) by using a visual analogue scale (VAS) at the beginning of the study period. The patients were asked to report their adherence to medication using a VAS. The adherence was then monitored by using a Medical Event Monitoring System (MEMS) for 42+/-14 d. The means+/-SD (range) of MEMS measures for timing adherence, correct dosing, and adherence to medication were 82+/-27% (0 to 100%), 87+/-24% (4 to 100%), and 94+/-18% (4 to 108%), respectively. The physicians' prediction of their patients' adherence was 92+/-15%. The Spearman rank correlations between the physician's prediction and the MEMS measures of timing adherence, correct dosing, and adherence to medication was 0.42 (p=0.006), 0.47 (p=0.002), and -0.02 (p=0.888), respectively. The patients reported their own adherence to medication at 98+/-2% (range 83 to 100%). The Spearman correlations between the reported and actual behaviours were 0.27 (p=0.08) for timing adherence, 0.25 (p=0.12) for correct dosing, and 0.11 (p=0.51) for adherence to medication. The physicians' ability to predict patients' adherence to antihypertensive medication is limited and not accurate for identifying non-adherent patients in clinical practice. Even patients themselves are unable to give accurate reports of their own adherence to medication.

Shared-decision making in general practice: do patients with respiratory tract infections actually want it?

BACKGROUND: There is conflicting evidence on whether patients wish to be involved in medical decisions. METHODS: We interviewed 636 ambulatory patients with acute respiratory tract infections in cantons Basel-Stadt and Aargau. We asked whether they agreed with two statements that are the antithesis of shared-decision making. We used proportional odds regression to investigate how agreement with these two statements is associated with patient characteristics and with patient satisfaction and enablement. RESULTS: Many patients (66%) supported leaving decision making to their physician. These patients were more likely to be satisfied with the consultation and scored higher on enablement. Patients whose responses were consistent with a preference for shared-decision making were more likely to be younger, better educated and in more discomfort. CONCLUSION: Patients consulting a general practitioner for acute respiratory tract infections should be invited to participate in decision making although many may choose to decline.

Barriers to apply cardiovascular prediction rules in primary care: a postal survey.

BACKGROUND: Although cardiovascular prediction rules are recommended by guidelines to evaluate global cardiovascular risk for primary prevention, they are rarely used in primary care. Little is known about barriers for application. The objective of this study was to evaluate barriers impeding the application of cardiovascular prediction rules in primary prevention. METHODS: We performed a postal survey among general physicians in two Swiss Cantons by a purpose designed questionnaire. RESULTS: 356 of 772 dispatched questionnaires were returned (response rate 49.3%). About three quarters (74%) of general physicians rarely or never use cardiovascular prediction rules. Most often stated barriers to apply prediction rules among rarely- or never-users are doubts concerning over-simplification of risk assessment using these instruments (58%) and potential risk of (medical) over-treatment (54%). 57% report that the numerical information resulting from prediction rules is often not helpful for decision-making in practice. CONCLUSION: If regular application of cardiovascular prediction rules in primary care is in demand additional interventions are needed to increase acceptance of these tools for patient management among general physicians.

Students' satisfaction with general practitioners' feedback to their reflective writing: a randomized controlled trial.

BACKGROUND: Reflective Writing (RW) is increasingly being implemented in medical education. Feedback to students' reflective writing (RW) is essential, but resources for individualized feedback often lack. We aimed to determine whether general practitioners (GPs) teaching students clinical skills could also provide feedback to RW and whether an instruction letter specific to RW feedback increases students' satisfaction. METHODS: GPs were randomized to the two study arms using block randomization. GPs in both groups received an instruction letter on giving students feedback on clinical skills. Additionally, intervention group GPs received specific instructions on providing feedback to students' RW. Students completed satisfaction questionnaires on feedback received on clinical skills and RW. T-tests were employed for all statistical analysis to compare groups. RESULTS: Eighty-three out of 134 physicians participated: 38 were randomized to the control, 45 to the intervention group. Students were very satisfied with the feedback on RW and clinical skills regardless of tutors' group allocation. A specific instruction letter had no additional effect on students' satisfaction. CONCLUSION: Based on student satisfaction, GPs who give students feedback on clinical skills are also well suited to provide feedback on RW. This approach can facilitate the introduction of mandatory RW into the regular medical curriculum.

Communication training and antibiotic use in acute respiratory tract infections. A cluster randomised controlled trial in general practice.

UNLABELLED: A cluster-randomised controlled trial in general practice BACKGROUND: Physician-patient communication plays a key role in treatment decisions in primary care. We aimed to reduce the antibiotic prescription rate for acute respiratory tract infections using a short training programme in patient-centred communication. METHODS: We conducted a cluster-randomised controlled trial in 45 general practices in Switzerland. Thirty physicians received evidence-based guidelines for the management of acute respiratory tract infections; 15 physicians randomised to the full intervention additionally received training in patient-centred communication. A further 15 physicians, not randomised, served as a control to blind the physicians in the other two groups to the true comparison. The primary outcome was the antibiotic prescription rate reported by pharmacists. Secondary outcomes were patient satisfaction and enablement, re-consultation rates, days with restrictions, and days off work. 1108 adults with acute respiratory infections were screened between January and May 2004. Outcomes were measured in 837 consultations; 624 patients had follow-up interviews at 7 and 14 days. RESULTS: The antibiotic prescription rate reported by pharmacists was low in both full and limited intervention groups (13.5% and 15.7% respectively) but only half of the antibiotics were prescribed according to guidelines (53.8% and 53.1%). No significant differences were seen between the two randomised groups in primary and secondary outcomes. In both groups patient satisfaction was high (median score for both 68 out of 70). CONCLUSIONS: In this trial, patient-centred communication training did not reduce the rate of antibiotic prescriptions below an already unusually low level. Even with this low prescription rate, patient satisfaction with received care was high.

Prevalence and influence of diagnostic tests for acute respiratory tract infections in primary care.

BACKGROUND: General practitioners (GPs) use diagnostic tests to help distinguish between viral and bacterial acute respiratory tract infections (ARTI). We investigated the prevalence of these tests, and how tests are associated with diagnosis, treatment and patient satisfaction. METHODS: As part of a clinical trial, 45 GPs screened 1108 patients with ARTI and collected information on signs and symptoms, diagnostic test results, and subsequent diagnosis and treatment. A sample of 636 patients was interviewed after 7 days and their opinions recorded. We used multivariate mixed models to estimate associations between the use of tests and (1) baseline characteristics, (2) subsequent antibiotic treatment, and (3) patient satisfaction. RESULTS: GPs carried out at least one test in 42% of the 1108 patients screened. The tests used were (percentage of patients): CRP (35%), leucocyte count (17%), rapid Strep A (9%), chest X-ray (5%), sinus X-ray (1%), and throat culture (1%). The use of tests was associated with increasing patient age, education, and degree of discomfort. Antibiotic therapy was strongly associated with a positive test, with odds ratios of 26 (95% CI, 10-67) for a CRP above 50 mg/l; 9.6 (95% CI, 3.6-26) for a leucocyte count above 10,000/microl; and 122 (4.4-3435) for a positive StrepA test. There was no evidence of an association between the use of tests and patient satisfaction. CONCLUSIONS: Nearly half of these patients with ARTI received a diagnostic test. Older patients, those with higher education and those in more discomfort were more likely to get tests. A positive test was strongly associated with antibiotic treatment.

Effect of amoxicillin-clavulanate in clinically diagnosed acute rhinosinusitis: a placebo-controlled, double-blind, randomized trial in general practice.

BACKGROUND: Acute rhinosinusitis is one of the most common reasons for prescribing antibiotics in primary care. However, it is not clear whether antibiotics improve the outcome for patients with clinically diagnosed acute rhinosinusitis. We evaluated the effect of a combination product of amoxicillin-potassium clavulanate on adults with acute rhinosinusitis that was clinically diagnosed in a general practice setting. METHODS: We conducted a randomized, placebo-controlled, double-blind trial with 252 adults recruited at 24 general practices and 2 outpatient clinics. Each patient had a history of purulent nasal discharge and maxillary or frontal pain for at least 48 hours. Patients were given amoxicillin, 875 mg, and clavulanic acid, 125 mg, or placebo twice daily for 6 days. Main outcome measures were time to cure (primary outcome), number of days during which rhinosinusitis restricted activities at home or work, and frequency of adverse effects (secondary outcomes). RESULTS: The adjusted hazard ratio for the effect of amoxicillin-clavulanate was 0.99 (95% confidence interval [CI], 0.68-1.45) on time to cure and 1.28 (95% CI, 0.80-2.05) in the prespecified subgroup of patients with a positive rhinoscopy result. At 7 days the mean difference between amoxicillin-clavulanate and placebo was -0.29 (95% CI, -0.93 to 0.34) in the number of days with restrictions due to rhinosinusitis and -0.60 (95% CI, -1.41 to 0.21) in patients with a positive rhinoscopy result. At 7 days patients who took amoxicillin-clavulanate were more likely to have diarrhea (odds ratio, 3.89; 95% CI, 2.09-7.25). CONCLUSIONS: Adult patients in general practice with clinically diagnosed acute rhinosinusitis experience no advantage with antibiotic treatment with amoxicillin-clavulanate and are more likely to experience adverse effects.

Patients' expectations about the benefit of antibiotic treatment: lessons from a randomised controlled trial.

BACKGROUND: Patient expectations may be an important component of a placebo effect, and yet few studies assess how patients' pre-existing expectations affect subsequent health outcomes. OBJECTIVES: To estimate the association between patients' expectations and time to cure in patients with clinically diagnosed acute bacterial rhinosinusitis. METHODS: In a randomised controlled trial, expectations about the benefit of an antibiotic therapy were measured prior to treatment with either an antibiotic or placebo. RESULTS: Of the patients asked for consent, 64% refused mostly because they either wanted or did not want to receive antibiotics. Over 25% of the patients who gave consent were ambivalent about the benefit of antibiotic therapy. Predictably there was no evidence of an association between expectations and time to cure in those that gave consent. CONCLUSIONS: Selection bias occurs if patients with strong expectations refuse to participate in a trial and if the success of the intervention depends in part on a patient's expectations. Methods that adjust for selection bias are recommended for trials where placebo effects are either of interest or could be an important component of an intervention.

The clinical diagnosis of acute bacterial rhinosinusitis in general practice and its therapeutic consequences.

In a randomized double-blind trial 251 adults with sinusitis-like symptoms were given amoxicillin/clavulanate or placebo for 6 days. Seven diagnostic indicators for acute bacterial rhinosinusitis are compared by their accuracy assuming a latent class model and by the treatment effect that they would have had if used to select a subset of patients for antibiotic treatment. Under a latent class model, radiography is a more efficient indicator then C reactive protein (CRP), which is, in turn, more efficient than other clinical signs and symptoms. However, a history of purulent nasal discharge, and signs of pus in the nasal cavity and throat, are better criteria than radiography or CRP for selecting those patients who will benefit from antibiotic treatment. These contradictory results are a salutary reminder that diagnostic indicators need to be evaluated in terms of therapeutic consequences for the patient.

Occipitomental (Waters' view) radiographs from general practice: are they adequate?

Critics maintain that family physicians produce radiographic images of poorer technical quality than radiologists but the impact of lower quality images on patient care is unknown. Two radiologists assessed occipitomental radiographs made in either a general practice or a certified laboratory for 247 patients with clinically diagnosed acute bacterial rhinosinusitis. With an occipitomental radiograph correct positioning is more difficult than with the usual radiographs of chest or extremities commonly made in general practice. Good positioning was less common in radiographs from general practices, with the pyramid projected below the maxillary sinuses in 63% of radiographs from general practice and 79% of radiographs from a certified laboratory. However, a radiographic diagnosis of possible acute maxillary sinusitis was as common in radiographs from general practice (38%) as in radiographs from a certified laboratory (41%). Although routine use is not recommended, family physicians with suitable technical and interpretative skills can use an occipitomental radiograph to rule out acute maxillary sinusitis in difficult cases. With a radiograph that is hard to read the physician should act as if the disease is present or refer the radiograph to a consulting radiologist.

Use of volumetric capnography to identify pulmonary dysfunction in horses with and without clinically apparent recurrent airway obstruction.

OBJECTIVE: To investigate whether volumetric capnography indices could be used to differentiate between horses without recurrent airway obstruction (RAO) and horses with RAO that were in clinical remission or that had clinically apparent RAO. ANIMALS: 70 adult Swiss Warmblood horses (20 used for pleasure riding and 50 used for dressage or show jumping). PROCEDURE: Horses were allocated to 4 groups on the basis of history, clinical signs, results of endoscopy, and cytologic findings (group 1, 21 healthy horses; group 2, 22 horses with RAO that were in remission; group 3, 16 horses with mild RAO; group 4, 11 horses with exacerbated RAO). Expiratory volume and CO2 curves were recorded by use of a computerized ultrasonic spirometer. Volumetric capnograms were plotted, and derived indices were calculated. RESULTS: Dead-space volume (VD) was calculated by use of the Bohr equation (VD(Bohr)) and for physiologic VD (VD(phys)). Ratios for VD(Bohr) to expiratory tidal volume (VT) and VD(phys) to V(T) as well as an index of effective CO2 elimination were significantly different among groups of horses. Age and use of the horses also significantly affected volumetric capnography indices. CONCLUSIONS AND CLINICAL RELEVANCE: Ratios of VD(Bohr) to VT and VD(phys) to VT as well as an index of effective CO2 elimination were sufficiently sensitive measures to distinguish between healthy horses and horses with RAO in remission. To optimize the ability of volumetric capnography indices to differentiate among horses in heterogeneous populations, it is important to account for effects of age and specific use of the horses.