| Methods |
Type of study: parallel RCT Stratification: randomisation was stratified by clinic and smoking status (whether subjects were smokers in the past 5 years) Sample size calculation: not reported Funding: NIDCR grant Country: USA Timeframe of the study: January 2003 to June 2005
(other methods detail: please see the risk of bias table) |
| Participants |
Centres: 5, the University at Buffalo, the University of North Carolina at Chapel Hill, Boston University, Kaiser Permanente Center for Health Research/Oregon Health and Sciences University, and the University of Maryland, Baltimore, Maryland Inclusion criteria: to be eligible for the study, participants had to satisfy cardiac and periodontal inclusion criteria. For the cardiovascular criteria, participants had to be ≤ 75 years of age with ≥ 50% blockage of one coronary artery or have had a coronary event within 3 years but ≥ 3 months previously, including myocardial infarction, coronary artery bypass graft surgery, or coronary transluminal angioplasty with or without a stent. The periodontal inclusion criteria were the presence of at least 6 natural teeth, including third molars, with at least 3 teeth with PPD ≥ 4 mm, at least 2 teeth with interproximal CAL ≥ 2 mm, and ≥ 10% of sites having BOP. The criteria were applied after accounting for tooth extractions that were deemed clinically necessary Exclusion criteria: not reported Participants type: moderate to severe periodontitis and CVD Number of participants: total 303; intervention group 151; control group 152 Gender of participants: total, male 216, female 87; intervention group 104/47; control group 112/40 Age of participants: total mean = 59.6±8.8 (SD); intervention group 59.5±9.1; control group 59.8±8.7 Lost to follow‐up: by the time of the 6‐month visit, 14 participants had withdrawn consent and 7 had been lost to follow‐up. They were all considered as drop‐outs. Among follow‐up participants, only 228 had clinical follow‐up. By the time of 1 year, only 37 had clinical follow‐up |
| Interventions |
Both groups had hopeless teeth extracted before randomisation Intervention group: oral hygiene instruction + full mouth SRP under local anaesthesia (30% of the treatment being completed > 2 months after randomisation; 92.7% of the participants received the treatment; 85% of them received supra‐gingival scaling) Control group (community care group): oral hygiene instruction and given a copy of their oral radiographs and a letter stating the tentative oral findings and recommended to seek the opinion of a dentist (9% of the participants in the control group got SRP outside the study within 6 months and 11% of them got SRP within the whole follow‐up process) Besides the study treatment, some participants sought dental care via other ways (such as their own dental providers); 1% of the participants in the intervention group got SRP outside the study and 9% (6 months) and 11% (whole study follow‐up) of the participants in the control group got SRP Duration of follow‐up: 6 to 25 months |
| Outcomes |
Cardiovascular SAE (all cardiovascular events, measured during the whole study (means 25 months follow‐up)) (the time frame was declared in the e‐mail from the trial authors) Serum hs‐CRP (measured by latex‐enhanced nephelometry at baseline, 6 months and 1 year) Number of participants with high hs‐CRP (serum hs‐CRP > 3 mg/l measured at baseline, 6 months and 1 year) AE (the development of an undesirable medical/dental condition or the deterioration of a pre‐existing medical/dental condition following or during exposure to a pharmaceutical product or medical/dental procedure, whether or not considered causally related to the intervention, measured during the whole study) SAE (an experience that is known with certainty or suspected with good reason to constitute a threat to life or to cause severe or permanent damage, measured during the whole study) |
| Notes |
The author provided extra information about the study |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Quote: "Randomization was stratified by clinic and smoking status (whether subjects were smokers in the past 5 years). A permuted block randomization scheme was used with a random mixture of block sizes within each stratum." In authors' letter "the randomization was by computer using a random number generator in SAS" Comment: random number generation was adequate, low risk of bias |
| Allocation concealment (selection bias) |
Low risk |
Quote: "Clinical centre staff obtained treatment assignments through a Web‐based system designed and maintained by the coordinating centre. When a participant was deemed eligible, a staff member used the Web interface to enter the eligibility information, and the system returned the treatment assignment" Comment: the allocation concealment was adequately achieved, low risk of bias |
| Blinding of participants and personnel (performance bias) All outcomes |
High risk |
|
| Blinding of outcome assessment (detection bias) All outcomes |
Low risk |
Quote: in authors' letter "the outcome assessment was blinded" Comment: the previous protocol stated that the study was a single‐blind study, low risk of bias |
| Incomplete outcome data (attrition bias) All outcomes |
Unclear risk |
Comment: in 6 months, 16/152 (10.5%) in the control group, 5/151 (3.3%) in the intervention group were lost to follow‐up, and only 228/303 got clinical follow‐up. In 1 year, only 37/303 got clinical follow‐up. The follow‐up status at other time points was unclear. It is not clear whether there was a significant difference between the study groups in losses to follow‐up, unclear risk of bias
|
| Selective reporting (reporting bias) |
Low risk |
|
| Other bias |
High risk |
Comment: only 92.7% of the participants in the intervention group received the treatment, 1% of the participants in intervention group got SRP outside the study and 9% (6 months) and 11% (whole study follow‐up) of the participants in control group got SRP. Therefore this study had contamination and co‐intervention, high risk of bias
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