In an attempt to improve the management of dyslipidemias in patients with CHD or at high-risk for developing future CVD events, specialty clinics have been developed within many institutions. Studies evaluating the effectiveness of these specialty clinics have demonstrated significant improvements in lowering LDL-C levels, achieving lipid targets, and reducing other cardiac risk factors compared to usual care (Shaffer and Wexler 1995
; Harris et al 1998
; Wilson et al 1999
; Yates et al 2001
; Gavish et al 2002
; Koren and Hunninghake 2004
; Olson et al 2005
). While the evidence clearly demonstrates that specialty cardiovascular risk reduction or lipid clinics are very effective in managing patients with dyslipidemias and other risks for CVD, all published evaluations of these practices have focused on the outcomes achieved while the patients are managed within the clinic. The present study demonstrated that the improvements achieved in all lipid parameters during attendance at the CRRC were maintained in both high-risk and moderate-risk patients over a median follow-up of 1.28 years. During this time patients were seen in the clinic for a mean of 3.6 visits and received an additional 4.1 clinic telephone contacts.
The very high frequency of medication use by the CRRC is one probable explanation for the significant change in lipids observed in the patients during clinic follow-up. An average of 1.5 lipid-lowering medications/patient used during CRRC follow-up reflects a high rate of medication change for efficacy or toxicity reasons, as well as the need for combination therapy in many patients (19.1%). In a previous study within our population, we demonstrated that commonly prescribed combination regimens (statin + fibrate and statin + niacin) were safe and effective when patients are well informed about the potential toxicities and judiciously monitored (Taher et al 2002
). Not surprisingly, statins were the class of lipid-lowering agents most commonly prescribed, used in >82% of our patients. In addition to lipid-lowering therapy medication recommendations and adjustments, the significant changes in the lipid profiles observed in the clinic might also be attributed to the structured, one-to-one education and counseling that patients received with the CRRC multidisciplinary team for dietary modification, alcohol consumption, exercise, and smoking cessation during clinic follow-up.
As the primary outcome, we assessed the effectiveness of the CRRC in managing dyslipidemias in 1,064 patients over a 10-year period, demonstrating statistically significant improvements in all lipid parameters. These improvements were achieved over a median of 2.41 years following last clinic follow-up. We successfully obtained the recent lipid profiles, measured ≥6 months after discharge from the CRRC, from referring primary care physicians for 39% of the eligible patients. The reasons for follow-up lipid profile results not being obtained in the other 653 patients were provided. Interestingly, there were 83 patients (7.8%) still under the referring physician’s care in whom no recent follow-up lipid screen had been ordered. The lack of follow-up lipid screening is surprising, since it is standard practice for the clinic physicians to recommend the referring physician continue to assess the patients’ lipid profile every 6 to 12 months after discharge from the clinic. However, given the patient volume and busy clinical practices of most primary care physicians, some may have delayed ordering follow-up up lipid panels for longer periods of time because they or their patients had the general impression that the lipid profiles were already optimized.
The worst-case analysis, in which the missing follow-up lipid values for 653 patients were imputed, demonstrated that approximately 50% of the improvement in the lipid parameters was lost between discharge and follow-up for the entire study population of 1064 patients. This observation is not surprising since we imputed the original baseline values for 653 patients (61.4%) in this analysis; however, one could argue that we should have expected to have observed a greater loss in the benefit in the mean lipid levels in this cohort following discharge, consistent with the proportion of patients for whom the baseline lipid values were imputed. This analysis demonstrated that overall change in each lipid parameter between the initial clinic visit and follow-up remained both statistically and clinically significant.
Based on data from a meta-analysis by Baigent and colleagues (2005)
, the 0.97 mmol/L mean reduction in LDL-C that was observed in the 411 patients in whom follow-up lipid profiles were obtained () would be expected to result in an 18.4% reduction in CHD mortality and a 11.6% reduction in all-cause mortality after 5 years of treatment; however, based on our worst-case analysis (), the 0.39 mmol/L would be expected to reduce CHD mortality by 7.4% reduce all-cause mortality 4.7% after 5 years of treatment. Undeniably, these statistically significant changes in lipid parameters should translate into clinically significant improvements in patient outcomes over time.
No attempt was made in this study to determine the percentage of patients who successfully achieved their cholesterol goals given that there were no published guidelines for lipid targets during the earlier years of the clinic and guideline recommendations at various times over the 10-year study period were different. This was a retrospective evaluation; therefore, this study is subject to the same limitations as any retrospective study. However, the CRRC has been consistently staffed by a relatively small number of physicians who followed the same general charting procedures during the study period. In addition, the investigators utilized both inpatient and outpatient clinic charts to obtain the patient data which broadened the source of reliable documentation. We were unable to determine if there were other variables in addition to attending the CRRC, which may have influenced the sustained benefits that were observed in the lipid profiles of follow-up patients. Given the consistency in all lipid parameters between the final in-clinic results and the most recent profiles following CRRC discharge, it seems logical to assume that both patients and referring physicians adhered to the recommendations implemented in the clinic; however, we cannot definitively state that there were not other factors that contributed to this sustained benefit. While it was beyond the scope of this study to determine medication and lifestyle modification adherence among patients, this information would be helpful in determining how much of the observed long-term lipid improvements were the result of the CRRC management efforts. Finally, this study was conducted in a single clinic with its own unique patient referral biases, specific clinic experiences, and multidisciplinary staffing pattern which may potentially limit the generalizability of these findings to other specialty clinic practices. The findings of our study may only be applicable to other multidisciplinary clinics, which utilize a similar multifactorial risk-reduction model.
The results of this study suggest that a formally structured CRRC has a significant positive impact on improving important lipid parameters. These improvements appear to be sustained over the long-term after patients are discharged from the CRRC. This evidence lends support to the belief that patients can be discharged from these clinics once they are optimally managed, without compromising the improvements achieved in their CV risk profile. Given that the goal of specialty lipid clinics is to prevent cardiac events in patients with CHD or at high-risk for developing CVD in the future, discharging patients once they have their CV risks optimally managed will facilitate a greater number of patients being seen and benefiting from the multidisciplinary, structured approach to risk reduction provided by such clinics.