Monitoring method

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MONITORING METHOD

This is a continuation of application Ser. No. 08/525,371, filed on Sep. 7, 1995, which was abandoned upon the filing hereof which was a Division of application Ser. No. 08/109, 5 503, filed Aug. 20,1993, now U.S. Pat. No. 5,467,778 issued Nov. 21, 1995

This invention relates to methods, devices and test kits for use in monitoring the ovulation cycle in female mammals, especially humans.

The invention is particularly, although not solely, concerned with the provision of reliable information concerning fertility status as an aid to contraception, by the use of simple practical procedures that can readily be applied by unskilled persons, e.g. in the home.

Throughout this specification, the expression "fertile 15 phase" is used to mean that interval in a female menstrual cycle, spanning the event of ovulation, during which it is most likely that intercourse will result in fertilization, because of the normal viability of spermatozoa and ova.

To provide reliable information concerning fertility 20 status, the user must be given adequate warning of the onset of the fertile phase in the cycle. In general the proposed techniques rely on the monitoring of one or more parameters which alter as the event of ovulation approaches. Typical parameters which have been invoked are the concentration 25 of a body fluid analyte, such as estradiol and metabolites thereof, for example estrone-3-glucuronide (E3G). Other parameters that have been used are basal body temperature and various physiological changes such as the characteristics of vaginal mucous. 30

Many excellent academic studies have been carried out using such parameters. Such studies have established how these parameters can be correlated with the fertility status of an average member of a large population sample.

However, when attempting to develop a practical moni- 35 taring system suitable for use by individuals, it is found that many individual subjects do not conform to the average in terms of cycle length and/or the duration and timing of the fertile phase. The extent of variation from one individual to another, and indeed, from one cycle to another in the same 40 individual, renders average population data too unreliable for practical use.

A further factor that can vary widely from individual to individual is the threshold or baseline level of a parameter that is chosen as a testable characteristic which can signal 45 the onset of the fertile phase. Again, although it may be possible to set an average threshold or baseline level from population data, this may be quite inappropriate for individual needs.

It is an objective of the present invention to establish a 50 method of monitoring the ovulation cycle, useful for contraceptive purposes, which is tailored to the relevant characteristics of an individual subject by taking into account the foregoing possible variables.

Another important objective of the invention is to pro- 55 vide reliable fertility status while avoiding the necessity for tests to be conducted on a frequent (eg. daily) basis throughout every ovulation cycle. The necessity for regular, e.g. daily, testing throughout the cycle has characterised many ovulation cycle monitoring systems previously proposed. 60

There is a wealth of scientific literature on the urinary hormone profiles during the ovulation cycle. The relative usefulness of estradiol derivatives, especially estrone-3glucuronide (E3G), lutenising hormone (LH), and progesterone derivatives, especially pregnanediol-3-glucuronide 65 (P3G), as indicators of the status of the cycle, has been studied extensively.

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Procedures are already available commercially to enable LH to be used to enhance the likelihood of conception.

The article "A prospective multicentre study to develop universal tests for predicting the female period in women" (WHO, Int J Fertil 30(3) 1985 p 18-30) discusses the prediction of the fertile phase in an ovulation cycle by measuring the daily levels of the hormones E3G and Pd-3-G (ie. P3G) in early morning urine. Although the primary purpose of this study is to analyse for differences in fertile phase calculation in different races of women, this paper does suggest that the relative levels of E3G and Pd-3-G may be used in predicting the start and end of the fertile phase. If the start of the fertile phase is defined by the sustained rise in the level of urinary E3G, then the end of that fertile phase (ie the start of the luteal phase) may be assumed to be 5 days after the E3G peak is observed. Similarly, if the start of the fertile phase is taken to be an increase in the E3G: Pd-3-G ratio, the end is defined as being 6 days after the peak value of this index is observed.

The article "New assays for identifying the fertile phase" by Brown, Blackwell, Holmes and Smyth (Int J Gynecol Obstet 1989 Suppl 1 plll-122) discusses the use of oestrogen level measurements as an ovulation predictor, although oestrogen on its own is stated as being an unreliable ovulation predictor. Pregnanediol is also suggested as a hormone marker to signify the end of the fertile phase. In the studies referred to in this paper, the average number of days of abstinence from intercourse per menstrual cycle was seventeen; furthermore, the user satisfaction with this method of contraception, and the willingness of test couples to continue using it, was found to be inversely related to length of the abstinence period. Daily hormone measurements were made, although the article does speculate that, when the fertile phase is predicted by E3G and P3G measurements, that 12 tests per month may be sufficient. In an effort to get the abstinence period down to the quoted "theoretical" minimum of seven days, it is suggested that it may be possible to use a method of fertile phase prediction using a combination of cervical mucus symptoms and nonsymptomatic markers.

The article "Biochemical Indices of Potential Fertility" by Collins (Int J Gynecol Obstet, 1989, Suppl. 35^13) discusses the possible use of multiple analytes in urine to delineate the fertile phase. However, the tests carried out had a success rate in predicting the fertile phase of around 80% or less; also, the fertile phase predicted (and hence the abstinence period) was in all cases more than 10 days.

EP 367 615 (Monoclonal Antibodies Inc) provides a method of natural birth control in which the level of a urinary metabolite (progesterone) is measured as an indicator or the stage reached in the menstrual cycle. However, the only hormones suggested are progesterone metabolites, and hence the method can only be an indicator of the luteal phase safe period.

The article "Fertility Awareness: Jet-Age Rhythm Method?" by Djerassi (Science, Jun. 1, 1990, p 1061-2) suggests the prediction of the fertile phase for contraceptive, and in particular conception purposes by the analysis of body fluids (eg blood, urine or saliva). In this article, it is suggested that the start of the fertile phase could be predicted safely by detecting the rise in estradiol (or its metabolites). The start of the luteal phase could be predicted by either a second increase in estradiol concentration, or a major increase in progesterone (or its metabolites).

The clear inferences to be drawn from this literature are: estradiol and its metabolites, especially E3G, are the only urinary hormones that can be used to provide suffi3

ciently early warning, during the pre-ovulation phase of the cycle, for contraceptive purposes; and any successful fertility awareness test which aims to provide adequate contraceptive information, must involve measurement of E3G or an equivalent 5 molecule, and must identify the rise in E3G concentration that precedes ovulation. Nevertheless, the literature (for example, Djerassi) also indicates that no satisfactory test based on E3G has yet been developed. 10

It is generally accepted that the background level of urinary E3G fluctuates so widely from individual to individual that no simple, universally applicable assay can be devised.

To try to overcome this problem, complicated mathemati- 15 cal procedures, eg. "CUSUM", have been evolved to calculate a threshold E3G concentration during a current ovulation cycle, and to identify any significant rise above the calculated threshold. Such systems have the disadvantage that by the time the mathematics has recognised that a 20 significant rise is taking place, it may already be "too late" if the objective is contraception. Accordingly, it is generally accepted that the CUSUM approach cannot provide prospective information about fertility status. A review of CUSUM-based methods is found in Royston: Statistics in 25 Medicine, Vol. 10 (1991) 221-240.

Overall, from this general survey of the prior art, it can be seen that in previously known techniques of fertile phase prediction, the period predicted is unduly long, giving rise to an unduly long period of abstinence. Very often, such as for 30 example shown in EP 367 615, the long period of abstinence extends from menstruation to the end of the fertile phase. This, in part, is due to the difficulty in pinpointing the start of the fertile phase. It has also been a feature of prior art methods that frequent, often daily, measurements of urinary 35 hormone levels throughout the current cycle have been necessary for the method to be deemed reliable as a method of contraception.

In the provision of reliable contraceptive advice, it is clearly very important that a monitoring method should give 40 adequate warning of the onset of a fertile phase which happens to occur significantly in advance of normal. In this instance "normal" may be defined either in terms of population data, or normal for the individual subject herself.

The tendency has been to exercise extreme caution and to 45 require testing of the relevant parameters throughout the cycle, and particularly right from the onset of the cycle (onset of menses). From the individual user's point of view, it is clearly advantageous if the necessity for such constant testing could be avoided and, instead, for the testing to be 50 performed over a comparatively brief portion of each cycle. Not merely may this benefit the user in terms of convenience, but the cost of the method may also be reduced if, for example, fewer disposable testing devices are required each month. 55

In principle, based on population information, it should be possible to reduce the number of tests required by deciding that tests are unnecessary until a universally defined numerical day, or other specified time interval, following the onset of menses. However, as indicated above, individual varia- 60 tion tends to make any such universal assumption unsafe.

For the purposes of this specification, estradiol and all measurable estradiol metabolites, will collectively be referred to henceforth as "E3G". In addition to estrone-3glucuronide already mentioned, estradiol metabolites that 65 can also be assayed for the pruposes of the invention include estradiol-3-glucuronide, estriol-17-glucuronide, estriol-3

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glucuronide, estriol-16-glucuronide and (principally for non-human subjects) estrone-3-sulphate. As will be appreciated from the following description, the invention can readily be applied to data derived from the measurement of body fluid concentrations of other analytes of significance in relation to the status of the ovulation cycle. Generally, the most suitable analytes are hormones and their metabolites. Follicle stimulating hormone (FSH) is an example. Examples of alternative body fluids, which are relatively accessible, are saliva, crevicular fluid, sweat, sebum, tears and vaginal fluid. In principle internal fluids, such as blood, can be used but are generally not preferred because they can only be accessed readily by invasive techniques.

The skilled reader will also appreciate that the body fluid "concentration" of the chosen analyte or analytes need not be measured in absolute terms, although this can of course be done if desired. Generally, it will be sufficient to assay an analyte in a manner which yields a signal, convertible to numerical data, related to the actual concentration, so that such data can be compared with similar data obtained at a different stage in the cycle to determine whether or not a significant change in actual concentration has occurred. Accordingly, where the specification and claims below refer to the "concentration" of an analyte, this expression should be interpreted broadly.

The invention provides a method of monitoring the status of a current ovulation cycle of an individual mammalian female subject, involving repeated testing of the body fluid concentration of at least one analyte of significance in relation to the status of the ovulation cycle during at least the pre-ovulation phase of the current ovulation cycle of the individual subject, wherein testing for said analyte concentration during the current ovulation cycle is commenced a plurality of days following the onset of menses but at least 2 numerical days in advance of the earliest numerical day on which actual ovulation has occurred in one or more previous ovulation cycles in the same individual subject; and an analyte concentration change indicative of imminent ovulation is identified from the results of such testing by reference to an analyte concentration reference value that has been adapted to the individual subject on the basis of analyte concentration test data obtained from the individual subject during one or more previous ovulation cycles.

The invention also provides a test kit comprising:

a) one or more testing devices for determining the concentration of said at least one analyte in said body fluid,

b) means enabling a user to derive from said concentration an indication of fertility status in the current ovulation cycle by reference to a concentration reference value determined from one or more previous ovulation cycles in the same subject; and

c) means enabling a user to derive a precise testing commencement day from knowledge of the numerical day on which actual ovulation occurred during at least one previous ovulation cycle in the same subject.

Conveniently, in such a test kit, wherein means b) and c) are combined, and ideally comprise electronic means programmed for use in a method according to the invention.

In a further embodiment, the invention provides an electronic means for use in a method of monitoring the status of a current mammalian ovulation cycle, programmed to process analyte concentration test data obtained from testing of a body fluid conducted during at least part of the preovulation phase of the current cycle and to identify via said processing an analyte concentration change indicative of imminent ovulation, relative to an analyte concentration reference value that is adapted to an individual subject on the 5

basis of analyte concentration test data obtained from the individual subject during one or more previous ovulation cycles, and also to identify an analyte testing commencement day falling a plurality of days following the onset of menses in the current ovulation cycle but at least 2 numerical 5 day on which actual ovulation has occured in one or more previous ovulation cycles in the same individual subject.

Another aspect of the invention is a device for monitoring the human ovulation cycle, comprising means for initiating the recording of a cycle, means for measuring (if necessary 10 in conjunction with one or more testing devices readable by the monitoring device) and recording urinary E3G concentration, means for determining a threshold urinary E3G concentration from measurements taken during the infertile and transition phases of at least one preceding cycle, 15 and means for alerting a user if a measured urinary E3G concentration during the pre-fertile phase of a current cycle exceeds the determined threshold, means for measuring (if necessary in conjunction with one or more testing devices readable by the monitoring device) and recording urinary 20 LH and/or P3G concentration, means for determining from such LH and/or P3G concentration the earliest numerical day on which actual ovulation occurred in one or more previous ovulation cycles, and means for alerting a user to an optimum E3G testing commencement day in the current 25 cycle, said optimum E3G testing commencement day being at least 5 numerical days following the onset of menses in the current cycle but at least 2 numerical days in advance of said earliest numerical day on which actual ovulation occurred. 30

The analyte concentration may be measured in absolute terms, or in relative terms e.g. as a ratio relative to the concentration of a reference analyte present in the same sample of body fluid.

More generally, the invention includes any comparable 35 method in which a body fluid characteristic (e.g. viscosity, ionic strength, or conductivity) of significance in relation to the status of the ovulation cycle, is compared to a reference value that is adapted to an individual subject on the basis of test data obtained from the individual subject during one or 40 more previous ovulation cycles.

Optionally, the appropriate reference value, eg threshold, is derived from data obtained from a "rolling" reference base consisting of a fixed number of consecutive cycles immediately preceding the current cycle. Preferably this rolling 45 reference base consists of the immediately preceding 4 to 10 cycles, more preferably the immediately preceding 5 or 6 cycles. By having such a rolling reference base, any progressive "drift" in the appropriate threshold in the individual concerned can be picked up. For example, the threshold for 50 the next cycle can be an average of the thresholds suggested by the previous data, optionally weighted in favour of the most recent cycle or cycles.

Preferably, the method relies solely on the results of urine tests. 55

Preferably, the method does not involve the measurement of basal body temperature, especially as such measurement generally needs to be conducted throughout each cycle.

Preferably, the analyte is estradiol or a metabolite thereof, such as estrone-3-glucuronide. 60

A further embodiment of the invention is electronic means for use in a method of monitoring the status of a current mammalian, eg human, ovulation cycle, programmed to process analyte concentration test data obtained from testing of a body fluid conducted during at least part of the pre- 65 ovulation phase of the current cycle, and to identify via said processing an analyte concentration change indicative of

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imminent ovulation, relative to an analyte concentration reference value that is adapted to an individual subject on the basis of analyte concentration test data obtained from the individual subject during one or more previous ovulation cycles.

Preferably, the electronic means is incorporated in a recording device having means to record the results of analyte concentration tests, and means to display information concerning the status of the current ovulation cycle of an individual subject whose analyte concentration has been tested. Preferably, the recording device has means to measure the result of an analyte concentration test conducted using a testing device presented to the recording device.

The invention includes a body fluid analyte concentration testing device when used in conjunction with an electronic means and recording device combination of the invention, which testing device comprises a body fluid sample collecting means and an immunochromatographic testing means which provides the test result in a form readable by the test result measuring means of the recording device.

Another aspect of the invention is a test kit for providing awareness of the status of a current mammalian, eg human, ovulation cycle, comprising one or more testing devices for determining the concentration (in relative or absolute terms) in a body fluid of an analyte of significance in relation to the status of the ovulation cycle, together with electronic means programmed to process analyte concentration test data obtained during at least part of the pre-ovulation phase of the current cycle and to identify therefrom an analyte concentration change indicative of imminent ovulation, relative to an analyte concentration reference value that is adapted to an individual subject on the basis of analyte concentration test data obtained from the individual subject during one or more previous ovulation cycles.

Preferably the test kit comprises a plurality of disposable body fluid testing devices.

In a particularly preferred test kit of the invention, wherein the principal analyte is estradiol or a metabolite thereof, such as E3G, usually measured in urine, the testing devices additionally test the urinary LH concentration of the individual subject, and the LH concentration test results so obtained are used by the electronic means in conjunction with the other analyte concentration test results.

An important aspect of the invention is a method of predicting the fertile phase during a current ovulation cycle of an individual mammalian, eg human, subject by detecting, in the pre-ovulation phase, a body fluid concentration change of an analyte of significance in relation to the status of the ovulation cycle, wherein the concentration change is determined by reference to a threshold concentration determined for the individual subject from measurements of the analyte concentration in the body fluid during the pre-ovulation phase of at least one previous ovulation cycle. Preferably the analyte is urinary E3G, in which event the urinary E3G threshold concentration adopted for the current cycle is preferably the concentration that is, in a previous ovulation cycle, exceeded more frequently during the total number of days constituting the transition phase of that previous cycle than during the same number of days in the infertile phase immediately preceding said transition phase.

The invention includes a device for monitoring the mammalian, eg human, ovulation cycle, comprising means for initiating the recording of a cycle, means for measuring (if necessary in conjunction with one or more testing devices readable by the monitoring device) and recording urinary E3G concentration, means for determining a threshold uri