The influence of intrauterine contraception on the prevalence and severity of dysmenorrhea: a longitudinal population study.

STUDY QUESTION
Does intrauterine contraception influence the prevalence and severity of dysmenorrhea?


SUMMARY ANSWER
In this longitudinal study, a copper intrauterine device (Cu-IUD) did not influence the severity of dysmenorrhea, whereas the levonorgestrel-releasing intrauterine system (LNG-IUS) reduced dysmenorrhea severity.


WHAT IS KNOWN ALREADY
Dysmenorrhea is a common problem among young women. The LNG-IUS has been reported to be associated with less painful menstruation, although more long-term studies are necessary. In contrast Cu-IUDs have been reported to exacerbate dysmenorrhea.


STUDY DESIGN, SIZE, DURATION
A longitudinal population study. The prevalence and severity of dysmenorrhea was compared in a longitudinal analysis of variance performed in the same women when using either intrauterine contraception (Cu-IUD or LNG-IUS) or combined oral contraceptives (COCs) with other methods of contraception or no contraception.


PARTICIPANTS/MATERIALS, SETTING, METHODS
Random samples of 19-year-old women born in 1962 (n = 656), 1972 (n = 780) and 1982 (n = 666) assessed at 5-year intervals between 1981 and 2001. Current severity of dysmenorrhea was assessed on each occasion by a verbal multidimensional scoring system (VMS) and by a visual analog scale (VAS).


MAIN RESULTS AND THE ROLE OF CHANCE
Dysmenorrhea severity was unchanged in the same woman when using a Cu-IUD compared with using other methods (= condom use, barrier methods, natural family planning, coitus interruptus and sterilization)/no method of contraception in the longitudinal analysis of factors influencing dysmenorrhea severity (VMS score: +0.05 units/VAS: -0.3 mm, both NS). LNG-IUS and COC use were associated with reduced dysmenorrhea severity compared with other methods/no method (LNG-IUS use, VMS score: -0.4 units/VAS: -13 mm, both P < 0.01; COC use, VMS score: -0.4 units/VAS: -11 mm, both P < 0.0001). Childbirth reduced dysmenorrhea (VMS score: -0.3 units, P < 0.05/VAS: -16 mm, P < 0.001). Dysmenorrhea severity decreased between the ages of 19 and 44 years.


LIMITATIONS, REASONS FOR CAUTION
There was a decline in the response rate over time during the 20 years of this longitudinal study which may be due to the fact that the distribution of questionnaires has become much more common and people are becoming increasingly tired of answering questionnaires. No information about the diagnosis or treatment of endometriosis or adenomyosis, which are important confounding factors, were included in the questionnaire. In this study we specifically studied dysmenorrhea and have clearly separated this from the assessment of possible pain caused by intrauterine contraception experienced between periods. RCTs should be initiated to further investigate the influence of intrauterine contraception on dysmenorrhea and the risk of developing abdominal pain between periods.


WIDER IMPLICATIONS OF THE FINDINGS
In this study Cu-IUD use did not influence the severity of dysmenorrhea and the LNG-IUS was shown to reduce the severity of dysmenorrhea. This is valuable information for prescribers and users when considering intrauterine contraception.