Clomiphene citrate and intrauterine insemination (IUI): how well does it work?

For those of you out there who have questions on Clomid (Clomiphene Citrate , Serophene) and it's efficacy here is an excellent piece of research out of Harvard Medical School. It is a retrospective study and therefore has limitations but i think it gives a great idea of what the chances are of concieving with clomid. Here is the abstract below (Source Fertility and Sterility via MEDLINE). As usual relevant parts are Highlighted in bold by me.

Clomiphene citrate and intrauterine insemination: analysis of more than 4100 cycles.

OBJECTIVE: To evaluate the outcomes of a large cohort of patients undergoing fertility treatment with clomiphene citrate and intrauterine insemination. DESIGN: A retrospective cohort study. SETTING: Boston IVF, a large university-affiliated reproductive medicine practice. PATIENT(S): A total of 4,199 cycles performed in 1,738 infertility patients between September 2002 and July 2007. INTERVENTION(S): All patients received oral clomiphene citrate, and patients with completed cycles had intrauterine insemination performed. MAIN OUTCOME MEASURE(S): Cumulative and per cycle pregnancy rates achieved among subsets of patients defined by age, completed cycles, and intention to treat (ITT). RESULT(S): For women under age 35 years, 2,351 cycles were initiated in 983 patients. A total of 238 pregnancies ensued, yielding a pregnancy rate (PR) per completed cycle of 11.5% and 10.1% per cycle initiated with ITT. In women aged 35-37 years, 947 cycles in 422 women lead to a PR per completed cycle and ITT of 9.2% and 8.2%, respectively. For patients aged 38-40 years, 614 cycles in 265 women lead to a PR per completed cycle and ITT of 7.3% and 6.5%, respectively. In women aged 41-42 years, 166 cycles in 81 patients lead to a PR per completed cycle and ITT of 4.3% and 3.6%, respectively. For women above age 42 years, 120 cycles in 55 patients lead to a PR per completed cycle and ITT of 1.0% and 0.8%, respectively. On a per-patient treated basis, cumulative PRs were 24.2% under age 35, 18.5% ages 35-37, and 15.1% ages 38-40, whereas only 7.4% ages 41-42 and 1.8% above 42 became pregnant (one pregnancy in 55 patients). CONCLUSION(S): As anticipated, younger patients have a higher PR per cycle than older patients. The PR per cycle for patients who initiate only one or only two treatment cycles is notably higher than the corresponding per cycle rates for cycles 3 through 9. The drop in success per patient among 41- and 42-year-olds is sharp, but the exceptionally low success rate above age 42 suggests that CC with IUI has virtually no place in their treatment.

Overall this is a very good article. I am not sure i agree 100% with all of its conclusions which are a bit drastic.
I do agree, and other data supports this, that most people who get pregnant on clomid get pregnant on the first 3 cycles.
I think that the overall pregnancy rates may vary for different populations and depending on the way physicians practice. For example in my practice were we do not immediately jump to ivf pregnancy rates for inseminations are consistently higher. Some ivf physicians divert patient who have poor prognoses to iui in order not affect their center's pregnancy rates and this lowers the iui rates.
The issue on how to approach the over 42 patients is complex and furthermore (sadly) much has to deal with insurance coverage and resources. Over 42 patients are a heterogeneous group : a minority of them have good ovarian reserve whereas the majority has poor or no reserve. Although patients are very aware of this reality they often opt to try their luck. Obviously this represents a philosophical decision: the pragmatist will opt for oocyte donation whereas the more idealistic will try with their own eggs and a few lucky ones will succeed.
For what pertains the actual benefit of utilizing ovulation induction in the patients over 44 I think the verdict is still not out.