delivered the opinion of the court:
Defendants, J. I. Weimer, M.D., and R. K. Taubert, M.D., appeal the jury verdict against them in the amount of $300,000. They cite numerous alleged errors at trial. Plaintiff, Betty Witherell, appeals the trial court’s reduction of her award on the basis of comparative fault. The trial court also held section 2 — 1205 of the Code of Civil Procedure (Ill. Rev. Stat. 1983, ch. 110, par. 2—1205) to be unconstitutional. We reverse.
This is the second appeal in this case. The prior appeal concerned the circuit court’s grant of the defendant doctors’ motion to dismiss. This court reversed, and the supreme court affirmed. (Witherell v. Weimer (1979), 77 Ill. App. 3d 582, 396 N.E.2d 268, aff'd (1981), 85 Ill. 2d 146, 421 N.E.2d 869.) Upon remand, a jury trial was held. The jury found in favor of the plaintiff and awarded her $500,000 in damages. The jury also apportioned 40% of the damages to her own negligence, thus reducing the award to $300,000.
The first issue we shall deal with concerns the application of the statute of limitations to the present case. Among other contentions, defendants claim that a bifurcated hearing on the issue should have been held, and that the jury erred in its findings. We find, however, that we are precluded from addressing these issues, as they are barred *34due to res judicata. The supreme court decided the issue in one concise statement. “In our opinion, generally accepted principles of equitable estoppel prevent the defendant doctors from urging the limitations bar.” (Witherell v. Weimer (1981), 85 Ill. 2d 146, 158, 421 N.E.2d 869.) The court further stated that “fundamental fairness require[s] that the defendant doctors be held estopped by their conduct from now arguing that plaintiff should have sooner complained against them for a condition they repeatedly assured her she did not have.” 85 Ill. 2d 146, 160, 421 N.E.2d 869.
It is readily apparent that the supreme court, by the two above quoted sentences, decided, as a matter of law, the statute of limitations would not act as a bar in this case. Defendants claim that the fact, adduced after the supreme court decision, that plaintiffs husband had a vasectomy in the early 1970’s should change the decision. We see no connection between the vasectomy and the defendant’s conduct. The supreme court’s holding was quite clear and unambiguous. “A question of law decided on a previous appeal is binding on both the trial court and the appellate court.” (Gord Industrial Plastics, Inc. v. Aubrey Manufacturing, Inc. (1984), 127 Ill. App. 3d 589, 591, 469 N.E.2d 389.) Both parties inexplicably spent a great portion of their argument, both oral and written, on this issue. We find that the supreme court disposed of the question in one simple sentence! It is res judicata.
The second issue deals with a constitutional question. The trial judge held section 2 — 1205 of the Code of Civil Procedure (Ill. Rev. Stat. 1983, ch. 110, par. 2—1205) to be unconstitutional as arbitrary and specific legislation. As such, it would be violative of the Constitution of 1970 (Ill. Const. 1970, art. IV, sec. 13.) Having found the statute to be infirm, the court denied defendants’ request for a setoff. Defendants also challenge this ruling.
Section 2 — 1205 allows a reduction of up to 50% of the amount of recovery for unsubrogated reimbursements for medical charges, hospital charges, etc. This section was enacted in response to the medical malpractice “crisis” of 1976. Guidance for our analysis is found in Anderson v. Wagner (1979), 79 Ill. 2d 295, 402 N.E.2d 570, a case which upheld the constitutionality of the repose provision in the statute of limitations enacted with the section presently under scrutiny. Cf. Mega v. Holy Cross Hospital (1986), 111 Ill. 2d 416.
The analysis of a claim of special legislation is similar to that of an equal protection claim. The legislature may regulate persons or objects in a class if there is a reasonable basis for doing so. (Anderson v. Wagner (1979), 79 Ill. 2d 295, 315, 402 N.E.2d 570.) In Anderson, the court found a reasonable basis to distinguish between physicians and hospitals and the general class of health-care providers. The statute was *35drawn narrowly to apply to those most affected by the malpractice explosion that existed. 79 Ill. 2d 295, 319, 402 N.E.2d 570.
The object of the legislation was to insure the continued availability of malpractice insurance to those who were affected by the multitude of claims and thus to insure the continuation of health services from those affected groups. (Anderson v. Wagner (1979), 79 Ill. 2d 295, 317, 402 N.E.2d 570.) Likewise, the obvious intention of section 2 — 1205 is to prohibit a double recovery of damages. Those who are injured and reimbursed, and will not recover twice for their reimbursed expenses, may be less likely to bring suit against their physician. With fewer suits and fewer double recoveries, malpractice premiums are not forced to increase, thus achieving the goal of the legislature, i.e., keeping malpractice insurance available to all practitioners.
The trial court relied primarily on Wright v. Central Du Page Hospital (1976), 63 Ill. 2d 313, 347 N.E.2d 736. The holding in Wright is clearly distinguishable from the present case. The Anderson court noted that Wright disapproved of the act because it would have been possible for the seriously injured to be unable to recover all medical expenses because of the $500,000 limit on recovery in malpractice cases. Anderson v. Wagner (1979), 79 Ill. 2d 295, 304-05, 402 N.E.2d 570.
In the present section, we have no such limit on the recovery of damages. The section does not hinder a plaintiffs right to a full recovery for his damages. It merely limits his recovery to those items for which he was not reimbursed. The section is thus a reasonable method of the legislature’s attempt to attain its goal. For this reason, we must reverse the trial court’s holding that section 2 — 1205 is unconstitutional.
The third and decisive issue concerns the cross-appeal. Plaintiff has cross-appealed the trial court’s acceptance of the verdict in regard to the question of comparative fault. Plaintiff claims that defendants did not generally or specifically plead and prove allegations of contributory négligence. The trial court noted that defendants had no duty to plead these allegations. The trial court also refused to place the burden of proof as to any contributory negligence upon defendants. The trial judge subsequently allowed the jury’s determination of the plaintiff’s negligence to stand.
The supreme court recently passed on the burden-of-proof issue in Casey v. Baseden (1986), 111 Ill. 2d 341. Casey found that plaintiffs were no longer obligated to plead and prove their freedom from contributory negligence. Thus, the burden of proving a plaintiff’s negligence was placed on defendants and the instruction given in Casey, placing the burden on the defendant, was proper. The court reasoned *36that comparative negligence is similar to a plaintiff’s duty to mitigate his damages. Since a defendant must prove a plaintiff’s failure to mitigate damages, a defendant “should likewise carry the burden on the plaintiff’s negligence.” 111 Ill. 2d 341, 347.
In the present case, the court refused to put the burden on the defendants. An instruction should have been given, however. At most, defendants were entitled to only a general instruction on comparative negligence. Thus, reversal is required. However, given the amount of fault assessed to the plaintiff, and the evidence supporting such an assessment, we are unwilling to simply reverse the finding of comparative fault. Equity dictates the case be remanded to give defendants the opportunity to prove the alleged negligence on plaintiff’s part, and the jury must make its decision from defendants’ proofs.
Plaintiff also contends that it was error for the court to allow the jury to consider plaintiff’s negligence as it was not put forth in the pleadings. We disagree. At the time of trial, defendants were not required to plead allegations of contributory negligence. Public Act 84— 624 amended section 2 — 613(d) of the Code of Civil Procedure (Ill. Rev. Stat. 1985, ch. 110, par. 2—613(d)) (effective September 20, 1985) to require that plaintiffs’ negligence must be treated as an affirmative defense. As there was then no burden upon defendants to plead the negligence at the time of trial, there was no error for the court to allow its presentation.
We have analyzed above the purely legal issues in this cause and must now turn to applying the law to the factual issues involved in the trial of this case.
Plaintiff’s medical history is involved and complex. In 1965, she complained of frequent episodes of hot flashes. She had a prior history of menstrual problems. In order to remedy this, defendant Dr. Weimer injected her with estrogen. She was also placed on a prescription of Ortho-Novum, a birth-control medication. Plaintiff continually saw defendant, reporting a variety of symptoms. Aside from the hot flashes, in 1965 she also suffered from pain in the knee and the neck. In 1966, she suffered pain in the throat and neck. In March 1967, she had her first attack of thrombophlebitis. Dr. Weimer felt that this was caused by a combination of the trauma she suffered in a beating by her husband and by a fall down some stairs.
Also in 1967, plaintiff attempted suicide. In 1969, plaintiff had an ovarian deficiency and chest pains. Between October 1966 and June 1969, when she suffered the ovarian deficiency, plaintiff received no estrogen injections from either Dr. Weimer or Dr. Taubert. In 1970, Dr. Taubert refilled her prescription. Dr. Weimer also administered estrogen injections in September and November 1970. Injections were also *37administered in February, July, August, October, and December of 1971.
Plaintiff was twice hospitalized in 1971, complaining of throm-bophlebitic symptoms. She was attended to by Dr. Ehmke, a neurologist, and Dr. Remolina. Dr. Ehmke found that plaintiff did not have thrombophlebitis, her problems were nonvascular, and that they were probably psychophysiological. Dr. Remolina, during the second hospitalization, found that she suffered a musculoskeletal reaction. Dr. Remo-lina also recommended outpatient psychiatric therapy.
Plaintiff had another bout with thrombophlebitis in 1972. She was hospitalized after a long auto trip. Dr. Taubert admitted her to Pekin Hospital, diagnosing thrombophlebitis caused by stasis. The condition resolved itself in six to eight days.
Plaintiffs next leg pain occurred in May 1973 following an auto accident. In May, she also required outpatient treatment for hip, lower back, and neck pain. Plaintiff additionally received acupuncture treatment. In September 1973 plaintiff was treated for leg pain by defendants’ deceased partner, Dr. Rhoades. He diagnosed sciatica and recommended diathermic treatment. Also in September, Dr. Weimer prescribed cyclospasmal for plaintiff’s poor circulation.
In April 1974 plaintiff saw psychiatrist Dr. Turow complaining of spasms and occipitalfrontal headaches. Turow found plaintiff to be preoccupied with physical problems. In May plaintiff complained of spasms and weakness in the shoulders and legs that were so bad that she could not work.
Plaintiff saw Dr. Taubert in March 1976 about a sore throat and chest pains. She was hospitalized that May with neuritis and myostisis. However, she complained of recurrent phlebitic symptoms. Dr. Weimer examined her for this, but he found no evidence of phlebitis, only tenderness. Dr. Clements, a resident in cardiology, also examined plaintiff during the hospitalization. He also found swelling in the leg, diagnosing it as caused by the electric-shock therapy to the leg administered by a chiropractor nine weeks before the hospitalization. Dr. Wright, a radiologist, examined a venogram of plaintiff’s leg. His analysis was that that clots in plaintiff’s leg were old and had recannalized. A possible cause of this was one prior episode of thrombophlebitis.
Plaintiff never saw defendants after this. She filed this action January 4,1978.
In May 1976 plaintiff was examined by Dr. Juco. He diagnosed active thrombophlebitis. In January 1977 Dr. Juco referred plaintiff to the Mayo Clinic. The examination revealed post-phlebitic syndrome. From March 1977 through March 1980 plaintiff saw Dr. Camacho, an internist. He found no evidence of active thrombophlebitis. He also *38thought that there might not be any organic cause to her problems. During that period, plaintiff also saw Dr. Beck, a psychiatrist, for treatment of anxiety and depression.
After seeing Dr. Camacho, plaintiff began seeing Dr. Cullinan, who was her treating physician up to the time of trial. Dr. Cullinan had plaintiff on an anticoagulation therapy of Coumadin. Her first leg problem while under his care arose in February 1982. Plaintiff took a 10-day trip by car to Florida. Her right leg was swollen, and she was admitted to the hospital. Dr. Cullinan found deep-vein thrombophlebitis and a possible pulmonary embolus. She was rehospitalized in September, but all tests on her legs proved normal.
In December 1982 plaintiff was in Champaign. She saw Dr. Houston, a hematologist, complaining of chest pain. Dr. Houston found plaintiff’s legs to be normal. No evidence of circulatory disease was found. Dr. Houston felt that plaintiff was psychologically dependent on her medications.
Plaintiff then saw Dr. Cullinan and Dr. Shay, a cardiologist, in December 1982 and January 1983. They found no evidence of active disease. In July 1983 plaintiff was again hospitalized, complaining of low back pain and of coughing up blood. Dr. Arthur Fox, a pulmonary disease specialist, found no evidence of pulmonary emboli. Dr. James R. DeBord, a vascular surgeon, found that blood flow in and out of her legs to be normal.
Another hospitalization occurred in August 1983. Dr. DeBord again found the blood flow to be normal. Dr. Duane Morgan, a pulmonary disease specialist, found no thrombosis nor venal insufficiency, and recommended stopping the anticoagulation therapy.
Plaintiff complained of chest pain and abdominal pain in December 1983 and was again hospitalized. Dr. Radie, a cardiologist, found no heart disease. Dr. Russo, a physical medical specialist, thought her problems to be the result of mechanical factors and arthritis. Dr. De-Bord found normal blood flow. This was the last hospitalization before trial.
It is quite clear from the record that the central issue relied on in plaintiff’s case was the relationship between the thrombophlebitis and the combination of estrogen and Ortho-Novum. Plaintiff’s contention is that the dispensing of the medications either caused or aggravated the thrombophlebitic episodes, and that it was negligent to continue their prescription. There was a great deal of evidence from both sides as to this issue.
However, we believe that the jury was improperly instructed on this issue. It is well settled that, in reviewing the instructions submitted to the jury, they should be viewed as a whole. (Curry v. Sum *39 mer (1985), 136 Ill. App. 3d 468, 483 N.E.2d 711.) The issues instruction set forth plaintiff’s allegations as follows:
“The plaintiff claims that she was injured and sustained damage, and that the defendants were negligent in one or more of the following respects:
a. Did not properly interpret, diagnose and treat the signs and symptoms of the plaintiff’s condition of thrombophlebitis in April and May of 1976.
b. Did not timely recognize the presence of thrombophlebitis in plaintiff’s legs in April and May of 1976.
c. Failed to prescribe drugs which were appropriate for the plaintiff, given her condition.
d. Continued to allow her to take birth control pills and estrogen notwithstanding that they knew that the plaintiff had thrombophlebitis or a past history of thrombophlebitis.”
The instructions then required the jury to find for the plaintiff if she proved any of the above allegations.
Nowhere is the jury required to make a finding that the prescription of estrogen and birth-control pills were the proximate cause of her injury or that her problems were aggravated by the medication. Defendants’ position was that, while she did suffer from episodes of thrombophlebitis, and while defendants continued the birth-control pill/ estrogen therapy, the medications had no injurious effect. Without requiring the jury to make a finding of causation, defendants’ position is an admission of liability under the above-stated issues. We therefore find this instruction unacceptable and improper.
We make this analysis under Supreme Court Rule 366 (87 Ill. 2d R. 366) which provides in pertinent part: “(a) Powers. In all appeals the reviewing court may, in its discretion, and on such terms it deems just *** (5) *** grant any relief *** that the cause may require.” (87 Ill. 2d R. 366(a)(5).) This rule has been held analogous to the plain-error doctrine in criminal review. (Schutzenhofer v. Granite City Steel Co. (1982), 93 Ill. 2d 208, 211, 443 N.E.2d 563.) We find that the issues instruction, if followed literally, deprives defendants of having their defense as to causation considered by the jury. The instructions, taken as a whole, do not cure this problem. As this discussion makes clear, we believe we have the right to exercise our discretion, analyze the issue, and decide the same even though neither of the parties to this appeal made an appropriate objection to the issues instruction. This issue, while not in and of itself dispositive of our decision, further supports the outcome, i.e., reversal and remandment, dictated by the legal holdings discussed above.
Because of our decision today, we decline to review all of defend*40ants’ other alleged errors. We shall examine those which are likely to recur on remand. The first concerns the use of the Physicians’ Desk Reference (PDR) in the trial. Defendants claim that the PDR was used to establish the standard of care through Dr. Laird, plaintiff’s pharmacological expert.
Defendants first claim that Dr. Laird was incompetent to establish standard-of-care testimony. This is based on the fact that Dr. Laird is not licensed to practice medicine in any State. This, defendants claim, renders him incompetent as a medical expert witness under the holding of Dolan v. Galluzzo (1979), 77 Ill. 2d 279, 396 N.E.2d 13. Dolan held that for an expert to testify, the expert must be licensed in the school of medicine in which (as hereinafter explained) the defendants belong.
Dr. Laird testified to his credentials. He received his M.D. in 1949 from Wayne State University School of Medicine. He served an internship at Detroit Receiving Hospital. He then received his master’s degree in Pharmacology in 1952 from Wayne State. He received his Doctorate in Pharmacology from the University of Michigan Medical School. He also taught pharmacology to medical students during that time, achieving the rank of assistant professor.
Dr. Laird served in the military in 1955 and 1956, practicing in the army in Kentucky for those years. He is now in the reserve corps, as an M.D. He additionally has worked for Sherman Laboratories and Parke Davis & Co. While at both jobs, he performed research, prepared data for the PDR, and was a part-time pharmacology professor. After leaving Parke Davis, Dr. Laird joined the full-time faculty at Wayne State, teaching pharmacology.
We find that given his experience, Dr. Laird was qualified to testify as to the pharmacological aspects of the present case. However, defendants point out that his testimony pertained to following the recommendations in the PDR. We find no error in the circumstance, based on the witness’ experience.
The rule in Dolan was explained in Bartimus v. Paxton Community Hospital (1983), 120 Ill. App. 3d 1060, 458 N.E.2d 1072. The rule was created to protect professionals licensed in one “school of medicine” from having their actions judged by one licensed in another “school of medicine.” Thus, in Dolan, an orthopedic surgeon was prevented from evaluating work of a podiatrist, as each is licensed under separate acts of this State. In Bartimus, an allopath, licensed under the same statute as the defendant osteopath, could testify as to standard of care testimony.
Dr. Laird’s testimony is not in violation of the rule of Dolan. Dr. Laird received an M.D., he had extensive practical and theoretical *41knowledge of pharmacology, and his teaching has prepared many medical students, presumably doctors now, for practice. He has also had practical experience as a physician, having practiced, and continuing to serve, in the army. Additionally, Dr. Laird did not evaluate the work of defendants.
For these reasons, defendants were not prejudiced by Dr. Laird’s pharmacological testimony. He was taught and teaches in the same school of medicine. His practical knowledge was gained under similar circumstances. Thus, the testimony of Dr. Laird was properly allowed.
Defendants next argue that plaintiff used the PDR to establish the standard of care. Our examination of the evidence reveals that this is not so. Dr. Laird stated that, since 1948, the PDR sets a guide by which physicians should guide their conduct in the use of medications. He then stated that prescribing estrogens to someone with a history of thrombophlebitis between 1968 and 1976 violated the standards in the PDR and was not in accord with prescribing medical literature. Dr. Laird’s testimony was that prescribing medications when faced with contraindications should not be done.
Plaintiff then established that following the recommendations in the PDR was the standard of care. They did so through the testimony of their other expert witness, Dr. Immesoete. The use of the PDR to establish prima facie evidence of negligence was approved in Ohligsch-lager v. Proctor Community Hospital (1973), 55 Ill. 2d 411, 303 N.E.2d 392. This is contrary to the general rule that the standard of care must be proved by expert testimony. In the present case, plaintiffs used the PDR to establish a standard of care. Dr. Immesoete then showed that, in defendant’s locale, the standard of care was that the PDR should be followed. Thus, plaintiff did use expert testimony to establish the standard of care.
The present case is distinguishable from a case heavily relied upon by defendants, Young v. Cerniak (1984), 126 Ill. App. 3d 952, 467 N.E.2d 1045. In Young, there was no evidence that following the recommendations of the PDR was the standard of care. Rather, the evidence showed that the PDR was merely a guide. In the instant case, Dr. Immesoete stated that there should be no deviation from the PDR. Thus, its use was not erroneous.
For the foregoing reasons, the judgment of the circuit court of Tazewell County is reversed. The cause is remanded for a new trial.
Reversed and remanded.
SCOTT, J., concurs.