Relatively little is known about the factors in Canada which lead to osteoporosis and its concomitant fractures. The Canadian Multicentre Osteoporosis Study (CaMos) is a prospective cohort study which will estimate the incidence and prevalence of declining bone mass and fractures. The impact of osteoporosis in Canada will be assessed, including regional variation and the effect of various risk factors. The study will provide information for developing prevention programs. The cohort has been drawn from a random population-based sample of non-institutionalized men and women 25 years old or more and living within 50 km. of nine cities in Canada. Through telephone interviews 9,423 participants have been recruited. All answered an extensive questionnaire, and had physical measurements related to bone quality taken. This paper details the CaMos baseline and five-year follow-up protocol.
Canadian Multicentre Osteoporosis Study CaMos methodology, population-based osteoporosis cohort study Canada bone density, fracture incidence prevalence Canadian prospective cohort, Prior Kreiger Tenenhouse CaMos osteoporosis study design, bone mass decline risk factors Canadian population, osteoporosis prevention epidemiology regional variation Canada, CaMos baseline protocol bone quality measurements, random population sample osteoporosis fracture prospective study, menopause bone health Canadian multicentre cohort
DOI 10.1017/S0714980800009934 10.1017/S0714980800009934
Cite this article
Kreiger, N., Tenenhouse, A., Joseph, L., Mackenzie, T., Poliquin, S., Brown, J. P., Prior, J. C., & Rittmaster, R. S. (1999). Research Notes: The Canadian Multicentre Osteoporosis Study (CaMos): Background, Rationale, Methods. Canadian journal on aging = La revue canadienne du vieillissement, 18(3), 376-387. https://doi.org/10.1017/S0714980800009934
Kreiger N, Tenenhouse A, Joseph L, Mackenzie T, Poliquin S, Brown JP, et al. Research Notes: The Canadian Multicentre Osteoporosis Study (CaMos): Background, Rationale, Methods. Can. J. Aging. 1999;18(3):376-387. doi:10.1017/S0714980800009934
Kreiger, N., et al. "Research Notes: The Canadian Multicentre Osteoporosis Study (CaMos): Background, Rationale, Methods." Canadian journal on aging = La revue canadienne du vieillissement, vol. 18, no. 3, 1999, pp. 376-387.
Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene (677C>T, 1298A>C) cause elevated plasma homocysteine concentrations and have been linked to fatal outcomes after nitrous oxide anesthesia. This study tested the hypothesis that patients with common MTHFR 677C>T or 1298A>C mutations develop higher plasma homocysteine concentrations after nitrous oxide anesthesia than wild-type patients. In this prospective, observational cohort study with blinded, mendelian randomization, the authors included 140 healthy patients undergoing elective surgery. All patients received 66% nitrous oxide for at least 2 h. The main outcome variable, plasma total homocysteine, and folate, vitamin B12, and holotranscobalamin II were measured before, during, and after surgery. After completion of the study, all patients were tested for their MTHFR 677C>T or 1298A>C genotype. Patients with a homozygous MTHFR 677C>T or 1298A>C mutation (n = 25) developed higher plasma homocysteine concentrations (median [interquartile range], 14.9 [10.0-26.4] microm) than wild-type or heterozygous patients (9.3 [7.5-15.5] microm; n = 115). The change in homocysteine after nitrous oxide anesthesia was tripled in homozygous patients compared with wild-type (5.6 microm [+60%] vs. 1.8 microm [+22%]). Only homozygous patients reached average homocysteine levels considered abnormal (> 15 microm). Plasma 5-methyl-tetrahydrofolate concentrations increased uniformly by 20% after nitrous oxide anesthesia, indicating the inactivation of methionine synthase and subsequent folate trapping. Holotranscobalamin II concentrations remained unchanged, indicating no effect of nitrous oxide on vitamin B12 plasma concentrations. This study shows that patients with a homozygous MTHFR 677C>T or 1298A>C mutation are at a higher risk of developing abnormal plasma homocysteine concentrations after nitrous oxide anesthesia.
To examine the risk of multiple sclerosis in users of combined oral contraceptives.
Cohort study conducted between 1968 and 1996 using diagnostic data supplied by General practices throughout the United Kingdom. Royal College of General Practitioners' Oral Contraception Study cohort of initially 46,000 women recruited during the late 1960s. Directly standardised incidence rates of multiple sclerosis were calculated for current, former and never-users of oral contraceptives using first ever cases of multiple sclerosis reported by the general practitioners. The standardisation variables were age, parity, social class and smoking history. Five-year survival rates in the different contraceptive groups were calculated using standard life table techniques. One hundred and fourteen first ever cases of multiple sclerosis had been reported by November 1996 during 564,000 woman-years of observation. The incidence rate in both current and former users was not materially different to that in never-users. Although based on limited evidence there was no suggestion that the five-year survival was affected by a woman's use of combined oral contraceptives. These findings do not suggest a greatly elevated risk of multiple sclerosis during, or after, use of combined oral contraceptives.
A 2-year international study involving NFP (natural family planning) associations in 5 countries (Canada Colombia France Mauritius U.S.) was conducted to evaluate statistically the effectiveness of the sympto-thermal method an NFP method which adds to the temperatiure method the observation of signs and symptoms of the ovulatory period. 1022 couples (21736 couples) were selected 1) the wife had to be between 19 and 44 years of age 2) the wife had to be of proven fertility by having carried a fetus for at least 28 weeks 3) the couple must have submitted 1 satisfactory temperature graphy before being accepted and 4) the couple must have expressed a willingness to submit temperature graphs for 2 years. 826 couples completed 24 months. Menstrual cycle length varied from 9 to 98 days with an average of 28.43 days. 205 women had a variation of 8 days or less. 128 unplanned pregnancies occured giving a rate of 7.47 conceptions/100 woman-years of exposure. Theoretical effectiveness was .93 pregnancies/100 woman-years using the Pearl Formula; 16 pregnancies occured in couples following instructions. Failure rate was 4.13% for couples trying to prevent pregnancies and 14.83% for couples only delaying a pregnancy. Failure rate of the method used alone was 7.16%; 8.19% used with other contraceptives. There was an average of 13 cycles per year per woman. Using the modified Pearl index (pregnancies per 1300 cycles rather than per 1200 months) the pregnancy rate was 7.66% vs. 7.47% for 1200 months. The study shows that the sympto-thermal method is effective and reliable. 2 1) whether a large group of people will accept a method that depends on periodic abstinence or 2) whether the method will be just as effective when used by couples who are not as well motivated as the participants in this study.